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Chapter: 8 -Problem: 7 >> Quantum cryptography requires having a photon gun that can, on demand, fire a single photon carrying 1 bit. In this problem, calculate how many photons a bit carries on a 250-Gbps fiber link. Assume that the length of a photon is equal to its wavelength, which for purposes of this problem, is 1 micron. The speed of light in fiber is 20 cm/nsec.
Answer Preview: At 250 Gbps a bit takes 4 10 12 sec to be transmitted With the speed of …

, Chapter: 8 -Problem: 22 >> A math class has 25 students. Assuming that all of the students were born in the first half of the year—between January 1st and June 30th— what is the probability that at least two students have the same birthday? Assume that nobody was born on leap day, so there are 181 possible birthdays.
Answer Preview: With 20 students there are 25 242 300 pairs of students The probability that the students in any p…

, Chapter: 8 -Problem: 30 >> Suppose an organization uses VPN to securely connect its sites over the Internet. Jim, a user in the organization, uses the VPN to communicate with his boss, Mary. Describe one type of communication between Jim and Mary which would not require use of encryption or other security mechanism, and another type of communication which would require encryption or other security mechanisms. Explain your a
Answer Preview: The VPN provides security for communication over the Int…

, Chapter: 8 -Problem: 4 >> Alice used a transposition cipher to encrypt her messages to Bob. For added security, she encrypted the transposition cipher key using a substitution cipher, and kept the encrypted cipher in her computer. Trudy managed to get hold of the encrypted transposition cipher key. Can Trudy decipher Alice’s messages to Bob? Why or why not?
Answer Preview: By getting hold of the encrypted key Trudy now kno…

, Chapter: 8 -Problem: 40 >> Is it possible to multicast a PGP message? What restrictions would apply?
Answer Preview: In order to multicast a PGP message one would have to …

, Chapter: 8 -Problem: 33 >> Two users can establish a shared secret key using the Diffie-Hellman algorithm, even if they have never met, share no secrets, and have no certificates (a) Explain how this algorithm is susceptible to a man-in-the-middle attack. (b) How would this susceptibility change if n or g were secret?
Answer Preview: a The information transferred from Alice to Bob is n…

, Chapter: 7 -Problem: 23 >> Although it was not mentioned in the text, an alternative form for a URL is to use the IP address instead of its DNS name. Use this information to explain why a DNS name cannot end with a digit.
Answer Preview: As mentioned an IP address is a set of four numbers separated b…

, Chapter: 7 -Problem: 40 >> An audio streaming server has a one-way ‘‘distance’’ of 100 msec to a media player. It outputs at 1 Mbps. If the media player has a 2-MB buffer, what can you say about the position of the low-water mark and the high-water mark?
Answer Preview: It takes 100 msec to get a pause command to the server …

, Chapter: 8 -Problem: 12 >> In the text, we computed that a cipher-breaking machine with a million processors that could analyze a key in 1 nanosecond would take 1016 years to break the 128-bit version of AES. Let us compute how long it will take for this time to get down to 1 year, still along time, of course. To achieve this goal, we need computers to be 1016 times faster. If Moore’s Law (computing power doubles every 18 m
Answer Preview: The equation 2 n 10 16 tells us n the number of doub…

, Chapter: 7 -Problem: 11 >> A binary file is 4560 bytes long. How long will it be if encoded using base 64 encoding, with a CR+LF pair inserted after every 110 bytes sent and at the end?
Answer Preview: The base 64 encoding will break the message into 1520 uni…

, Chapter: 8 -Problem: 6 >> You are a spy, and, conveniently, have a library with an infinite number of books at your disposal. Your operator also has such a library at his disposal. You have agreed to use Lord of the Rings as a one-time pad. Explain how you could use these assets to generate an infinitely long one-time pad.
Answer Preview: You could use ASCII representation of the characters in Lor…

, Chapter: 8 -Problem: 1 >> Break the following monoalphabetic substitution cipher. The plaintext, consisting of letters only, is an excerpt from a poem by Lewis Carroll. mvyy bek mnyx n yvjjyr snijrh invq n muvjvdt je n idnvy jurhri n fehfevir pyeir oruvdq ki ndq uri jhrnqvdt ed zb jnvy Irr uem rntrhyb jur yeoijrhi ndq jur jkhjyri nyy nqlndpr Jurb nhr mnvjvdt ed jur iuvdtyr mvyy bek pezr ndq wevd jur qndpr mvyy bek, medj be
Answer Preview: Will you walk a little faster said a whiting to a snail there a porpois…

, Chapter: 7 -Problem: 42 >> What is the bit rate for transmitting uncompressed 1200 × 800 pixel color frames with 16 bits/pixel at 50 frames/sec?
Answer Preview: The number …

, Chapter: 7 -Problem: 38 >> In Fig. 7-42(c), quantization noise occurs due to the use of 4-bit samples to represent nine signal values. The first sample, at 0, is exact, but the next few are not. What is the percent error for the samples at 1/32, 2/32, and 3/32 of the period? Figure 7-42(c) Transcribed Image Text: (c)
Answer Preview: The true values are sin2i32 for i from 1 t…

, Chapter: 8 -Problem: 2 >> An affine cipher is a version of a mono-alphabetic substitution cipher, in which the letters of an alphabet of size m are first map to the integers in the range 0 to m-1. Subsequently, the integer representing each plain text letter is transformed to an integer representing the corresponding cipher text letter. The encryption function for a single letter is E(x) = (ax + b) mod m, where m is the si
Answer Preview: Assume that the most frequent plaintext letter is e and the second most frequent letter …

, Chapter: 8 -Problem: 14 >> Suppose that a message has been encrypted using DES in counter mode. One bit of cipher text in block Ci is accidentally transformed from a 0 to a 1 during transmission. How much plain text will be garbled as a result?
Answer Preview: DES mixes the bits pretty thoroughly so a single …

, Chapter: 7 -Problem: 35 >> On the day of a major sporting event, such as the championship game in some popular sport, many people go to the official Web site. Is this a flash crowd in the same sense as the 2000 Florida presidential election? Why or why not?
Answer Preview: No In the sports case it is known months in advance that there wil…

, Chapter: 7 -Problem: 44 >> Consider a 50,000-customer video server, where each customer watches three movies per month. Two-thirds of the movies are served at 9 P.M. How many movies does the server have to transmit at once during this time period? If each movie requires 6 Mbps, how many OC-12 connections does the server need to the network?
Answer Preview: With 50000 customers each getting three movies per month the server outputs 150…

, Chapter: 8 -Problem: 17 >> Using the RSA public key cryptosystem, with a = 1, b = 2 . . . y = 25, z = 26. (a) If p = 5 and q = 13, list five legal values for d.(b) If p = 5, q = 31, and d = 37, find e. (c) Using p = 3, q = 11, and d = 9, find e and encrypt ‘‘hello’’.
Answer Preview: a For these parameters z 48 so we must choose d to be relatively prime to 48 Possible v…

, Chapter: 8 -Problem: 28 >> Alice wants to send a message to Bob using SHA-1 hashes. She consults with you regarding the appropriate signature algorithm to be used. What would you suggest?
Answer Preview: The recommended method would be by usin…

, Chapter: 8 -Problem: 32 >> The Diffie-Hellman key exchange is being used to establish a secret key between Alice and Bob. Alice sends Bob (227, 5, 82). Bob responds with (125). Alice’s secret number, x, is 12, and Bob’s secret number, y, is 3. Show how Alice and Bob compute the secret key.
Answer Preview: Bob knows that g x mod n 82 He computes 82 …

, Chapter: 8 -Problem: 18 >> Alice and Bob use RSA public key encryption in order to communicate between them. Trudy finds out that Alice and Bob shared one of the primes used to determine the number n of their public key pairs. In other words, Trudy found out that na = pa × q and nb = pb × q. How can Trudy use this information to break Alice’s code?
Answer Preview: Trudy can look up Alices and Bobs public key pairs and retrieve n a and n b B…

, Chapter: 8 -Problem: 39 >> Point-of-sale terminals that use magnetic-stripe cards and PIN codes have a fatal flaw: a malicious merchant can modify his card reader to log all the information on the card and the PIN code in order to post additional (fake) transactions in the future. Next generation terminals will use cards with a complete CPU, keyboard, and tiny display on the card. Devise a protocol for this system that mali
Answer Preview: The bank sends a challenge a long random number to the merchants computer …

, Chapter: 6 -Problem: 29 >> Describe two ways to get into the SYN RCVD state of Fig. 6-39. Figure 6-39 Transcribed Image Text: (Start) CONNECT/SYN (Step 1 of the 3-way handshake) CLOSED CLOSE/- LISTEN/- CLOSE/- SYN/SYN + ACK LISTEN (Step 2 of the 3-way handshake) RST/- SEND/SYN SYN SYN RCVD SENT SYN/SYN + ACK (simultaneous ope
Answer Preview: One way starts out with a LISTEN If a SYN is receive…

, Chapter: 6 -Problem: 46 >> Design and implement a chat system that allows multiple groups of users to chat. A chat coordinator resides at a well-known network address, uses UDP for communication with chat clients, sets up chat servers for each chat session, and maintains a chat session directory. There is one chat server per chat session. A chat server uses TCP for communication with clients. A chat client allows users to s
Answer Preview: Server Side Pseudo Code //Server Creates ServerSocket object for handling c…

, Chapter: 5 -Problem: 8 >> In Fig. 5-13 the Boolean OR of the two sets of ACF bits are 111 in every row. Is this just an accident here, or does it hold for all networks under all circumstances?  Figure 5-13 Transcribed Image Text: Send flags ACK flags Age Seq. A C F Data A Source 21 60 A 21 60 1 59 21 60 10 10 1 20 59 21
Answer Preview: It always holds If a packet has arrived on a line it …

, Chapter: 2 -Problem: 50 >> Using the spectral allocation shown in Fig. 2-52 and the information given in the text, how many Mbps does a cable system allocate to upstream and how many to downstream? Figure 2-52 Transcribed Image Text: 5 42 54 88 108 750 MHz 550 TV FM TV Downstream data Downstream frequencies Upstream frequenci
Answer Preview: The upstream bandwidth is 37 MHz Using …

, Chapter: 5 -Problem: 38 >> In IP, the checksum covers only the header and not the data. Why do you suppose this design was chosen?
Answer Preview: An error in the header is much more serious than an error in the data A bad address for e…

, Chapter: 1 -Problem: 30 >> What are the disadvantages of using small, fixed-length cells in ATM?
Answer Preview: Smallsized cells result …

, Chapter: 6 -Problem: 6 >> One criteria for deciding whether to have a server active all the time or have it start on demand using a process server is how frequently the service provided is used. Can you think of any other criteria for making this decision?
Answer Preview: One other criteria is how the client is affect…

, Chapter: 2 -Problem: 44 >> Suppose that A, B, and C are simultaneously transmitting 0 bits, using a CDMA system with the chip sequences of Fig. 2-28(a). What is the resulting chip sequence? Figure 2-28(a) Transcribed Image Text: A = (-1-1 -1 +1 +1-1 +1 +1) B = (-1-1 +1 –1 +1 +1 +1 -1) C = (-1 +1 -1 +1 +1 +1 -1 -1) D = (-1 +1
Answer Preview: The result is obtained by negating …

, Chapter: 6 -Problem: 14 >> Some other policies for fairness in congestion control are Additive Increase Additive Decrease (AIAD), Multiplicative Increase Additive Decrease (MIAD), and Multiplicative Increase Multiplicative Decrease (MIMD). Discuss these three policies in terms of convergence and stability.
Answer Preview: All three variants will oscillate across the efficiencyline None will converge t…

, Chapter: 7 -Problem: 22 >> Is it possible that when a user clicks on a link with Firefox, a particular helper is started, but clicking on the same link in Internet Explorer causes a completely different helper to be started, even though the MIME type returned in both cases is identical? Explain your answer.
Answer Preview: Yes it is possible Which helper is started depends on the co…

, Chapter: 5 -Problem: 21 >> A router can process 2 million packets/sec. The load offered to it is 1.5 million packets/ sec on average. If a route from source to destination contains 10 routers, how much time is spent being queued and serviced by the router?
Answer Preview: Here is 2 million and is 15 million so m is 075 and from q…

, Chapter: 8 -Problem: 5 >> Find a 77-bit one-time pad that generates the text €˜€˜Hello World€™€™ from the cipher text of Fig. 8-4. Figure 8-4 Transcribed Image Text: Message 1: Pad 1: Ciphertext: 1001001 0100000 1101100 1101111 1110110 1100101 0100000 1111001 1101111 1110101 0101110 1010010 1001011 1110010 1010101 1010010 11
Answer Preview: It is 1010011 0001…

, Chapter: 4 -Problem: 13 >> What is the baud rate of classic 10-Mbps Ethernet?
Answer Preview: Classic Ethernet uses Manchester …

, Chapter: 7 -Problem: 16 >> Is the vacation agent part of the user agent or the message transfer agent? Of course, it is set up using the user agent, but does the user agent actually send the replies? Explain your answer.
Answer Preview: The actual replies have to be done by the message transfer agent When …

, Chapter: 4 -Problem: 11 >> Six stations, A through F, communicate using the MACA protocol. Is it possible for two transmissions to take place simultaneously? Explain your answer.
Answer Preview: Yes Imagine that they are in …

, Chapter: 7 -Problem: 37 >> Assume that compression is not used for audio CDs. How many MB of data must the compact disc contain in order to be able to play two hours of music?
Answer Preview: CDquality stero audio needs 14 Mbp…

, Chapter: 5 -Problem: 12 >> Consider the network of Fig. 5-15(a). Imagine that one new line is added, between F and G, but the sink tree of Fig. 5-15(b) remains unchanged. What changes occur to Fig. 5-15(c) Figure 5-15 Transcribed Image Text: A A D (? G ? G M) ? (E D N (K K ? ? M (a) (b) (c) ?
Answer Preview: Node F currently has two descendants A and D It now ac…

, Chapter: 4 -Problem: 35 >> List some of the security concerns of an RFID system.
Answer Preview: One key security concern is unauthorized tracking of RFID …

, Chapter: 4 -Problem: 23 >> Give an example to show that the RTS/CTS in the 802.11 protocol is a little different than in the MACA protocol.
Answer Preview: RTSCTS in 80211 does not help with the exposed te…

, Chapter: 7 -Problem: 19 >> Consider the Chord circle of Fig. 7-71. Suppose that node 18 suddenly goes online. Which of the finger tables shown in the figure are affected? how? Figure 7-71 Transcribed Image Text: of successor 4 31 (30 29 Start Actual 3 0,1 node 3 4 28 Node 1's 5 finger (27 table 9. 12 5) 17 20 0,1 26 6 25 Node
Answer Preview: In the finger table for node 1 the node i…

, Chapter: 8 -Problem: 53 >> The purpose of this problem is to give you a better understanding as to the mechanisms of RSA. Write a function that receives as its parameters primes p and q, calculates public and private RSA keys using these parameters, and outputs n, z, d and e as printouts to the standard output. The function should also accept a stream of ASCII characters and encrypt this input using the calculated RSA keys.
Answer Preview: Here is a solution that demonstrates how to calculate the RSA keys and encrypt a stream of ASCII cha…

, Chapter: 7 -Problem: 14 >> Suppose that John just set up an auto-forwarding mechanism on his work email address, which receives all of his business-related emails, to forward them to his personal email address, which he shares with his wife. John’s wife was unaware of this, and activated a vacation agent on their personal account. Because John forwarded his email, he did not set up a vacation daemon on his work machine. Wha
Answer Preview: It depends on how the forwarding and vacation autoresponder are implemented In many cases the arrang…

, Chapter: 6 -Problem: 44 >> The file server of Fig. 6-6 is far from perfect and could use a few improvements. Make the following modifications.(a) Give the client a third argument that specifies a byte range.(b) Add a client flag ?w that allows the file to be written to the server. Figure 6-6 Transcribed Image Text: #includ
Answer Preview: (a) To give the client a third argument that specifies a byte range, we can modify the client-server …

, Chapter: 6 -Problem: 37 >> Suppose that you are measuring the time to receive a segment. When an interrupt occurs, you read out the system clock in milliseconds. When the segment is fully processed, you read out the clock again. You measure 0 msec 270,000 times and 1 msec 730,000 times. How long does it take to receive a segment?
Answer Preview: Compute the av…

, Chapter: 7 -Problem: 5 >> John wants to have an original domain name and uses a randomized program to generate a secondary domain name for him. He wants to register this domain name in the com generic domain. The domain name that was generated is 253 characters long. Will the com registrar allow this domain name to be registered?
Answer Preview: The generated name would probably be unique and sh…

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, Chapter: 5 -Problem: 17 >> Describe two major differences between the ECN method and the RED method of congestion avoidance.
Answer Preview: First the ECN method explicitly sends a congestion notific…

, Chapter: 1 -Problem: 11 >> The president of the Specialty Paint Corp. gets the idea to work with a local beer brewer to produce an invisible beer can (as an anti-litter measure). The president tells her legal department to look into it, and they in turn ask engineering for help. As a result, the chief engineer calls his counterpart at the brewery to discuss the technical aspects of the project. The engineers then report bac
Answer Preview: In the OSI protocol mod…

, Chapter: 5 -Problem: 45 >> Write a function to do forwarding in an IP router. The procedure has one parameter, an IP address. It also has access to a global table consisting of an array of triples. Each triple contains three integers: an IP address, a subnet mask, and the outline line to use. The function looks up the IP address in the table using CIDR and returns the line to use as its value.
Answer Preview: Forwarding is simply defined as the action applied by each router when a packet arrives at one of its interfaces . When a router receives a packet from one of its attached networks, it needs to forwar…

, Chapter: 7 -Problem: 29 >> Write an HTML page that includes a link to the email address username@DomainName. com. What happens when a user clicks this link?
Answer Preview: Here is one way to do it Click Here to ema…

, Chapter: 8 -Problem: 52 >> Write a function that accepts a stream of ASCII characters and encrypts this input using a substitution cipher with the Cipher Block Chaining mode. The block size should be 8 bytes. The program should take plain text from the standard input and print the cipher text on the standard output. For this problem, you are allowed to select any reasonable system to determine that the end of the input is r
Answer Preview: Answer: #include #include const int BLOCKSIZE = 8; //Function to encrypt a block of plain text using …

, Chapter: 3 -Problem: 15 >> Suppose that a message 1001 1100 1010 0011 is transmitted using Internet Checksum (4-bit word). What is the value of the checksum?
Answer Preview: To obtain the checksum we need to calculate the ones complement of the …

, Chapter: 2 -Problem: 13 >> Calculate the end-to-end transit time for a packet for both GEO (altitude: 35,800 km), MEO (altitude: 18,000 km) and LEO (altitude: 750 km) satellites.
Answer Preview: Transit time 2 AltitudeSpeed of li…

, Chapter: 4 -Problem: 42 >> In Fig. 4-48, the switch in the legacy end domain on the right is a VLAN-aware switch. Would it be possible to use a legacy switch there? If so, how would that work? If not, why not? Figure 4-48 Transcribed Image Text: Legacy frame ?? ?1 B5 B2 Tagged frame B4 Legacy B6 VLAN-aware bridge host and bri
Answer Preview: It would work Frames entering the core domain would …

, Chapter: 6 -Problem: 27 >> In Fig. 6-36 we saw that in addition to the 32-bit acknowledgement field, there is an ACK bit in the fourth word. Does this really add anything? Why or why not? Figure 6-36 Transcribed Image Text: 32 Bits Source port Destination port Sequence number Acknowledgement number CEUAPRS F WCRCSSYI REGKHTNN
Answer Preview: The ACK bit is used to tell whether the 32bit field is used But if it were not …

, Chapter: 4 -Problem: 31 >> Figure 4-24 shows several physical layer protocols. Which of these is closest to the Bluetooth physical layer protocol? What is the biggest difference between the two? Figure 4-24 Transcribed Image Text: Upper layers Logical link layer Data link layer MAC sublayer 802.11 (legacy) Frequency hopping a
Answer Preview: Bluetooth uses FHSS just a…

, Chapter: 2 -Problem: 21 >> The cost of a fast microprocessor has dropped to the point where it is now possible to put one in each modem. How does that affect the handling of telephone line errors? Does it negate the need for error checking/correction in layer 2?
Answer Preview: Traditionally bits have been sent over the line without any er…

, Chapter: 1 -Problem: 36 >> Search the Internet to find out some of the important peering points used for routing packets in the Internet at present.
Answer Preview: An Internet Exchange Point is where Internet networks come to…

, Chapter: 4 -Problem: 29 >> From Fig. 4-34, we see that a Bluetooth device can be in two piconets at the same time. Is there any reason why one device cannot be the master in both of them at the same time? Figure 4-34 Transcribed Image Text: Piconet 1 Piconet 2 ? ? Parked Active slave slave Bridge slave
Answer Preview: It is impossible for a device to be master in two piconets at th…

, Chapter: 4 -Problem: 14 >> Sketch the Manchester encoding on a classic Ethernet for the bit stream 0001110101.
Answer Preview: The signal is a squ…

, Chapter: 2 -Problem: 16 >> Prove that in 4B/5B encoding, a signal transition will occur at least every four bit times.
Answer Preview: Since 4B5B encoding uses NRZI there is a signal transition every time a 1 i…

, Chapter: 4 -Problem: 38 >> Consider the extended LAN connected using bridges B1 and B2 in Fig. 4-41(b). Suppose the hash tables in the two bridges are empty. List all ports on which a packet will be forwarded for the following sequence of data transmissions: (a) A sends a packet to C. (b) E sends a packet to F. (c) F sends a packet to E. (d) G sends a packet to E. (e) D sends a packet to A. (f) B sends a packet to F.
Answer Preview: a B1 will forward this packet on ports 2 3 and 4 B2 will forward it on 1 2 and 3 b B2 wil…

, Chapter: 2 -Problem: 33 >> Calculate the transmit time in the previous problem if packet switching is used instead. Assume that the packet size is 64 KB, the switching delay in the satellite and hub is 10 microseconds, and the packet header size is 32 bytes.
Answer Preview: The lowest bandwidth link 1 Mbps is the bottleneck With 64 KB packets there a…

, Chapter: 4 -Problem: 41 >> To make VLANs work, configuration tables are needed in the bridges. What if the VLANs of Fig. 4-47 used hubs rather than switches? Do the hubs need configuration tables, too? Why or why not? Figure 4-47 Transcribed Image Text: Gray station Gray and White port Hub G G -G W GW, Gray port GW B1 B2 -Whi
Answer Preview: No Hubs just connect all the incoming …

, Chapter: 8 -Problem: 50 >> Write a program that encrypts its input by XORing it with a key stream. Find or write as good a random number generator as you can to generate the key stream. The program should act as a filter, taking plain text on standard input and producing cipher text on standard output (and vice versa). The program should take one parameter, the key that seeds the random number generator.
Answer Preview: A stream cipher may be a trigonal key cipher wherever plaintext digits area unit combined with a p…

, Chapter: 1 -Problem: 29 >> Provide a list of reasons for why the response time of a client may be larger than the best-case delay.
Answer Preview: One reason is request or response messages may get corrupted or lost du…

, Chapter: 1 -Problem: 33 >> The ping program allows you to send a test packet to a given location and see how long it takes to get there and back. Try using ping to see how long it takes to get from your location to several known locations. From these data, plot the one-way transit time over the Internet as a function of distance. It is best to use universities since the location of their servers is known very accurately. Fo
Answer Preview: For the above-given list of websites, Ping has been made …

, Chapter: 4 -Problem: 28 >> List two ways in which WiMAX is similar to 802.11, and two ways in which it is different from 802.11.
Answer Preview: Like 80211 WiMAX wirelessly connects devices including mobile devices to the Inte…

, Chapter: 4 -Problem: 24 >> A wireless LAN with one AP has 10 client stations. Four stations have data rates of 6 Mbps, four stations have data rates of 18 Mbps, and the last two stations have data rates of 54 Mbps. What is the data rate experienced by each station when all ten stations are sending data together, and (a) TXOP is not used? (b) TXOP is used?
Answer Preview: a Each set of 10 frames will include one frame from each station If we let the time to send one fra…

, Chapter: 6 -Problem: 20 >> Several RPC implementations provide an option to the client to use RPC implemented over UDP or RPC implemented over TCP. Under what conditions will a client prefer to use RPC over UDP and under what conditions will he prefer to use RPC over TCP?
Answer Preview: A client will use RPC over UDP if the operation is id…

, Chapter: 7 -Problem: 15 >> In any standard, such as RFC 5322, a precise grammar of what is allowed is needed so that different implementations can inter work. Even simple items have to be defined carefully. The SMTP headers allow white space between the tokens. Give two plausible alternative definitions of white space between tokens.
Answer Preview: The first one is any sequence of one or more spaces …

, Chapter: 2 -Problem: 2 >> A noiseless 4-kHz channel is sampled every 1 msec. What is the maximum data rate? How does the maximum data rate change if the channel is noisy, with a signal-to-noise ratio of 30 dB?
Answer Preview: A noiseless channel can carry an arbitrarily large …

, Chapter: 3 -Problem: 18 >> A 1024-bit message is sent that contains 992 data bits and 32 CRC bits. CRC is computed using the IEEE 802 standardized, 32-degree CRC polynomial. For each of the following, explain whether the errors during message transmission will be detected by the receiver: (a) There was a single-bit error. (b) There were two isolated bit errors. (c) There were 18 isolated bit errors. (d) There were 47 isolat
Answer Preview: The CRC checksum polynomial is or degree 32 so a Yes CRC catches all singlebit err…

, Chapter: 4 -Problem: 19 >> Some books quote the maximum size of an Ethernet frame as 1522 bytes instead of 1500 bytes. Are they wrong? Explain your answer.
Answer Preview: The payload is 1500 bytes but when the …

, Chapter: 5 -Problem: 44 >> Write a program that simulates a computer network using discrete time. The first packet on each router queue makes one hop per time interval. Each router has only a finite number of buffers. If a packet arrives and there is no room for it, it is discarded and not re-transmitted. Instead, there is an end-to-end protocol, complete with timeouts and acknowledgement packets, that eventually regenerate
Answer Preview: #include #include #include #include #include #include #include #include #inc…

, Chapter: 1 -Problem: 19 >> The Internet is roughly doubling in size every 18 months. Although no one really knows for sure, one estimate put the number of hosts on it at 600 million in 2009. Use these data to compute the expected number of Internet hosts in the year 2018. Do you believe this? Explain why or why not.
Answer Preview: Doubling every 18 months means a factor of four gain in 3 years In 9 years the g…

, Chapter: 4 -Problem: 10 >> Consider five wireless stations, A, B, C, D, and E. Station A can communicate with all other stations. B can communicate with A, C and E. C can communicate with A, B and D. D can communicate with A, C and E. E can communicate A, D and B. (a) When A is sending to B, what other communications are possible? (b) When B is sending to A, what other communications are possible? (c) When B is sending to C
Answer Preview: For successful communication we require that the sender can reach communicate with the rec…

, Chapter: 2 -Problem: 6 >> What are the advantages of fiber optics over copper as a transmission medium? Is there any downside of using fiber optics over copper?
Answer Preview: Fiber has many advantages over copper It can handle much higher bandwidth than copper It is not a…

, Chapter: 7 -Problem: 46 >> Some cybersquatters have registered domain names that are misspellings of common corporate sites, for example, www.microsfot.com. Make a list of at least five such domains.
Answer Preview: www Goggle com w…

, Chapter: 1 -Problem: 27 >> Suppose the algorithms used to implement the operations at layer k is changed. How does this impact operations at layers k ? 1 and k + 1?
Answer Preview: This has no …

, Chapter: 3 -Problem: 14 >> Using the convolutional coder of Fig. 3-7, what is the output sequence when the input sequence is 10101010 (left to right) and the internal state is initially all zero? Figure 3-7 Transcribed Image Text: Output bit 1 ? Input bit s, S6 S4 S5 S2 S3 Output bit 2 ?
Answer Preview: When the first 1 goes in 11 comes out and S …

, Chapter: 1 -Problem: 1 >> Imagine that you have trained your St. Bernard, Bernie, to carry a box of three 8-mm tapes instead of a flask of brandy. (When your disk fills up, you consider that an emergency.) These tapes each contain 7 gigabytes. The dog can travel to your side, wherever you may be, at 18 km/hour. For what range of distances does Bernie have a higher data rate than a transmission line whose data rate (excludi
Answer Preview: The dog can carry 21 gigabytes or 168 gigabits A speed of 18 kmhour equals 0005 kmsec The …

, Chapter: 2 -Problem: 46 >> A CDMA receiver gets the following chips: (ˆ’1 +1 ˆ’3 +1 ˆ’1 ˆ’3 +1 +1). Assuming the chip sequences defined in Fig. 2-28(a), which stations transmitted, and which bits did each one send? Figure 2-28(a) Transcribed Image Text: A = (-1-1 -1 +1 +1-1 +1 +1) B = (-1-1 +1 –1 +1 +1 +1 -1) C = (-1 +1 -1 +1
Answer Preview: Just compute the four normalized inner products 1 1 3 …

, Chapter: 3 -Problem: 27 >> The distance from earth to a distant planet is approximately 9 × 1010 m. What is the channel utilization if a stop-and-wait protocol is used for frame transmission on a 64 Mbps point-to-point link? Assume that the frame size is 32 KB and the speed of light is 3 × 108 m/s.
Answer Preview: Link utilization 11 2BD BD bandwidthdelay …

, Chapter: 5 -Problem: 13 >> Compute a multicast spanning tree for router C in the following network for a group with members at routers A, B, C, D, E, F, I, and K. Transcribed Image Text: ? D A ? ? ?
Answer Preview: Multiple span…

, Chapter: 4 -Problem: 6 >> What is the length of a contention slot in CSMA/CD for (a) A 2-km twin-lead cable (signal propagation speed is 82% of the signal propagation speed in vacuum)?, (b) A 40-km multi mode fiber optic cable (signal propagation speed is 65% of the signal propagation speed in vacuum)?
Answer Preview: a Signal propagation speed in twin lead is 2 46 10 8 msec Sign…

, Chapter: 1 -Problem: 32 >> Find out what networks are used at your school or place of work. Describe the network types, topological, and switching methods used there.
Answer Preview: Computer Network is a digital resource sharing network which share data among different computers, i…

, Chapter: 2 -Problem: 47 >> In Figure 2-28, there are four stations that can transmit. Suppose four more stations are added. Provide the chip sequences of these stations. Figure 2-28 Transcribed Image Text: A = (-1-1 -1 +1 +1 -1 +1 +1) B = (-1 -1 +1-1 +1 +1 +1 -1) C = (-1 +1 -1 +1 +1 +1 -1 -1) D = (-1 +1 -1-1-1-1 +1 -1) (a) (b
Answer Preview: Here are the chip …

, Chapter: 5 -Problem: 43 >> Write a program to simulate routing using flooding. Each packet should contain a counter that is decremented on each hop. When the counter gets to zero, the packet is discarded. Time is discrete, with each line handling one packet per time interval. Make three versions of the program: all lines are flooded, all lines except the input line are flooded, and only the (statically chosen) best k lines
Answer Preview: Java : Algorithm : step1-enter the number of nodes in network step2-make matrix of network n*…

, Chapter: 2 -Problem: 18 >> A simple telephone system consists of two end offices and a single toll office to which each end office is connected by a 1-MHz full-duplex trunk. The average telephone is used to make four calls per 8-hour workday. The mean call duration is 6 min. Ten percent of the calls are long distance (i.e., pass through the toll office). What is the maximum number of telephones an end office can support? (A
Answer Preview: Each telephone makes 05 callshour at 6 minutes each Thus a telephone occupies a …

, Chapter: 4 -Problem: 32 >> It is mentioned in Section 4.6.6 that the efficiency of a 1-slot frame with repetition encoding is about 13% at basic data rate. What will the efficiency be if a 5-slot frame with repetition encoding is used at basic data rate instead?
Answer Preview: In a 5slot Bluetooth frame a maximum of 3125 625 5 bits …

, Chapter: 1 -Problem: 21 >> Mobile phone network operators need to know where their subscribers’ mobile phones (hence their users) are located. Explain why this is bad for users. Now give reasons why this is good for users.
Answer Preview: Having mobile phone operators know the location of users lets the operators learn much personal i…

, Chapter: 4 -Problem: 43 >> Write a program to simulate the behavior of the CSMA/CD protocol over Ethernet when there are N stations ready to transmit while a frame is being transmitted. Your program should report the times when each station successfully starts sending its frame. Assume that a clock tick occurs once every slot time (51.2 ?sec) and a collision detection and sending of a jamming sequence takes one slot time. A
Answer Preview: 1. Station h #ifndef STATION_H #define STATION_H using namespace std; class Station{ private: int _m…

, Chapter: 6 -Problem: 36 >> In a network whose max segment is 128 bytes, max segment lifetime is 30 sec, and has 8-bit sequence numbers, what is the maximum data rate per connection?
Answer Preview: A sender may not send m…

, Chapter: 2 -Problem: 53 >> Write a program to implement CDMA. Assume that the length of a chip sequence is eight and the number of stations transmitting is four. Your program consists of three sets of processes: four transmitter processes (t0, t1, t2, and t3), one joiner process, and four receiver processes (r0, r1, r2, and r3). The main program, which also acts as the joiner process first reads four chip sequences (bipolar
Answer Preview: code: import java util.*; public class CDMA { private int [][] wtable; private int [][] copy; private int [] channel_sequence; public void setUp( int …

, Chapter: 7 -Problem: 24 >> Imagine that someone in the math department at Stanford has just written a new document including a proof that he wants to distribute by FTP for his colleagues to review. He puts the program in the FTP directory ftp/pub/forReview/newProof.pdf. What is the URL for this program likely to be?
Answer Preview: We must guess the name of …

, Chapter: 1 -Problem: 37 >> Write a program that implements message flow from the top layer to the bottom layer of the 7-layer protocol model. Your program should include a separate protocol function for each layer. Protocol headers are sequence up to 64 characters. Each protocol function has two parameters: a message passed from the higher layer protocol (a char buffer) and the size of the message. This function attaches it
Answer Preview: Code is as follows : Written in C language. #include "stdio h" #include "stdlib h" #include "string h" #include "assert h" void application_layer_send…

, Chapter: 2 -Problem: 32 >> How long will it take to transmit a 1-GB file from one VSAT to another using a hub as shown in Figure 2-17? Assume that the up link is 1 Mbps, the down link is 7 Mbps, and circuit switching is used with 1.2 sec circuit setup time. Figure 2-17 Transcribed Image Text: Communication satellite 4 VSAT Hu
Answer Preview: The lowest bandwidth link 1 Mbps is the bot…

, Chapter: 1 -Problem: 34 >> Go to IETF’s Web site, www.ietf.org, to see what they are doing. Pick a project you like and write a half-page report on the problem and the proposed solution.
Answer Preview: Automated Network Management The number of network devices has significantly increased and continues …

, Chapter: 7 -Problem: 30 >> Write an XML page for a university registrar listing multiple students, each having a name, an address, and a GPA.
Answer Preview: One way of writing the XML …

, Chapter: 8 -Problem: 37 >> Alice is using the public-key authentication protocol of Fig. 8-43 to authenticate communication with Bob. However, when sending message 7, Alice forgot to encrypt RB. Trudy now knows the value of RB. Do Alice and Bob need to repeat the authentication procedure with new parameters in order to ensure secure communication? Explain your answer. Figure 8-43
Answer Preview: Even if Trudy intercepted the message including R B she …

, Chapter: 4 -Problem: 40 >> It is mentioned in Section 4.8.3 that some bridges may not even be present in the spanning tree. Outline a scenario where a bridge may not be present in the spanning tree.
Answer Preview: All bridges do participate in the spanning tree alg…

, Chapter: 1 -Problem: 23 >> An image is 1600 × 1200 pixels with 3 bytes/pixel. Assume the image is uncompressed. How long does it take to transmit it over a 56-kbps modem channel? Over a 1-Mbps cable modem? Over a 10-Mbps Ethernet? Over 100-Mbps Ethernet? Over gigabit Ethernet?
Answer Preview: The image is 1600 1200 3 bytes or 5760000 bytes This is …

, Chapter: 2 -Problem: 14 >> What is the latency of a call originating at the North Pole to reach the South Pole if the call is routed via Iridium satellites? Assume that the switching time at the satellites is 10 microseconds and earth’s radius is 6371 km.
Answer Preview: The call travels from the Nort h Pole to the satellite dir…

, Chapter: 2 -Problem: 23 >> What is the maximum bit rate achievable in a V.32 standard modem if the baud rate is 1200 and no error correction is used?
Answer Preview: Since there are 32 …

, Chapter: 5 -Problem: 18 >> A token bucket scheme is used for traffic shaping. A new token is put into the bucket every 5 ?sec. Each token is good for one short packet, which contains 48 bytes of data. What is the maximum sustainable data rate?
Answer Preview: With a token every 5 m sec …

, Chapter: 2 -Problem: 27 >> What is the percent overhead on a T1 carrier? That is, what percent of the 1.544 Mbps are not delivered to the end user? How does it relate to the percent overhead in OC-1 or OC-768 lines?
Answer Preview: With a modern T1 line the end users get 8 24 192 of th…

, Chapter: 2 -Problem: 52 >> Multiplexing STS-1 multiple data streams, called tributaries, plays an important role in SONET. A 3:1 multiplexer multiplexes three input STS-1 tributaries onto one output STS-3 stream. This multiplexing is done byte for byte. That is, the first three output bytes are the first bytes of tributaries 1, 2, and 3, respectively. the next three output bytes are the second bytes of tributaries 1, 2, and
Answer Preview: Program in Python that simulates a 3:1 multiplexer using pipes for communication among processes: import os import sys # Number of bytes in an STS-1 f…

, Chapter: 7 -Problem: 25 >> In Fig. 7-22, www.aportal.com keeps track of user preferences in a cookie. A disadvantage of this scheme is that cookies are limited to 4 KB, so if the preferences are extensive, for example, many stocks, sports teams, types of news stories, weather for multiple cities, specials in numerous product categories, and more, the 4-KB limit may be reached. Design an alternative way to keep track of pref
Answer Preview: Do it the way tomscasino does just pu…

, Chapter: 3 -Problem: 33 >> Compute the fraction of the bandwidth that is wasted on overhead (headers and re-transmissions) for protocol 6 on a heavily loaded 50-kbps satellite channel with data frames consisting of 40 header and 3960 data bits. Assume that the signal propagation time from the earth to the satellite is 270 msec. ACK frames never occur. NAK frames are 40 bits. The error rate for data frames is 1%, and the err
Answer Preview: With a 50kbps channel frames of 4000 bits and 8bit sequence numbers the p…

, Chapter: 1 -Problem: 35 >> The Internet is made up of a large number of networks. Their arrangement determines the topology of the Internet. A considerable amount of information about the Internet topology is available on line. Use a search engine to find out more about the Internet topology and write a short report summarizing your findings.
Answer Preview: Internet Topology is a set of relationships of structure, models or arrangements of …

, Chapter: 4 -Problem: 34 >> Suppose that there are 10 RFID tags around an RFID reader. What is the best value of Q? How likely is it that one tag responds with no collision in a given slot?
Answer Preview: We want to maximize the probability that one and only one tag respond…

, Chapter: 8 -Problem: 51 >> Write a procedure that computes the SHA-1 hash of a block of data. The procedure should have two parameters: a pointer to the input buffer and a pointer to a 20-byte output buffer. To see the exact specification of SHA-1, search the Internet for FIPS 180-1, which is the full specification.
Answer Preview: SHA-1 or Secure Hash Algorithm 1 is a cryptographic hash function which takes an input and produces a 160-bit (20-byte) hash value. This hash value is …

, Chapter: 6 -Problem: 35 >> To address the limitations of IP version 4, a major effort had to be undertaken via IETF that resulted in the design of IP version 6 and there are still is significant reluctance in the adoption of this new version. However, no such major effort is needed to address the limitations of TCP. Explain why this is the case.
Answer Preview: IP is a network level protocol while TCP is an endtoend transport level protocol An…

, Chapter: 2 -Problem: 34 >> In Fig. 2-40, the user data rate for OC-3 is stated to be 148.608 Mbps. Show how this number can be derived from the SONET OC-3 parameters. What will be the gross, SPE, and user data rates of an OC-3072 line? Figure 2-40 Transcribed Image Text: Data rate (Mbps) SONET SDH Electrical Optical Optical G
Answer Preview: Of the 90 columns 86 are available for user data in OC1 Thus the user capacit…

, Chapter: 3 -Problem: 38 >> A 100-byte IP packet is transmitted over a local loop using ADSL protocol stack. How many ATM cells will be transmitted? Briefly describe their contents.
Answer Preview: The AAL5 frame will consist of 2 PPP protcol bytes 100 …

, Chapter: 6 -Problem: 12 >> In Figure 6-20, suppose a new flow E is added that takes a path from R1 to R2 to R6. How does the max-min bandwidth allocation change for the five flows?
Answer Preview: Allocation for flow A will be …

, Chapter: 2 -Problem: 51 >> How fast can a cable user receive data if the network is otherwise idle? Assume that the user interface is (a) 10-Mbps Ethernet (b) 100-Mbps Ethernet (c) 54-Mbps Wireless.
Answer Preview: The downstream data rate of a cable user is the smaller of the downstream cable band…

, Chapter: 1 -Problem: 10 >> What are two reasons for using layered protocols? What is one possible disadvantage of using layered protocols?
Answer Preview: Among other reasons for using layered protocols using them leads to breaking up the de…

, Chapter: 2 -Problem: 19 >> A regional telephone company has 10 million subscribers. Each of their telephones is connected to a central office by a copper twisted pair. The average length of these twisted pairs is 10 km. How much is the copper in the local loops worth? Assume that the cross section of each strand is a circle 1 mm in diameter, the density of copper is 9.0 grams/cm3, and that copper sells for $6 per kilogram.
Answer Preview: The crosssection of each strand of a twisted pair is4 square mm A10km …

, Chapter: 8 -Problem: 46 >> You are given a text file of size 60 MB, which is to be encrypted using steganography in the low-order bits of each color in an image file. What size image would be required in order to encrypt the entire file? What size would be needed if the file were first compressed to a third of its original size? Give your answer in pixels, and show your calculations. Assume that the images have an aspect ra
Answer Preview: The number of bits to be encrypted is 60 10 6 8 480 10 6 bits Eac…

, Chapter: 7 -Problem: 10 >> A large law firm, which has many employees, provides a single email address for each employee. Each employee’s email address is @lawfirm.com. However, the firm did not explicitly define the format of the login. Thus, some employees use their first names as their login names, some use their last names, some use their initials, etc. The firm now wishes to make a fixed format, for example:firstname.l
Answer Preview: Naturally the firm does not want to provide an additional email account for each employe…

, Chapter: 5 -Problem: 20 >> The network of Fig. 5-34 uses RSVP with multicast trees for hosts 1 and 2 as shown. Suppose that host 3 requests a channel of bandwidth 2 MB/sec for a flow from host 1 and another channel of bandwidth 1 MB/sec for a flow from host 2. At the same time, host 4 requests a channel of bandwidth 2 MB/sec for a flow from host 1 and host 5 requests a channel of bandwidth 1 MB/sec for a flow from host 2. H
Answer Preview: The reservations from hosts 3 and 4 to host 1 share 2 MBsec of bandwid…

, Chapter: 2 -Problem: 15 >> What is the minimum bandwidth needed to achieve a data rate of B bits/sec if the signal is transmitted using NRZ, MLT-3, and Manchester encoding? Explain your answer.
Answer Preview: In NRZ the signal completes a cycle at most every 2 bits alternating 1s and 0s So t…

, Chapter: 7 -Problem: 48 >> Rewrite the server of Fig. 6-6 as a true Web server using the GET command for HTTP 1.1. It should also accept the Host message. The server should maintain a cache of files recently fetched from the disk and serve requests from the cache when possible. Figure 6-6 Transcribed Image Text: #include
Answer Preview: The server of Fig. 6-6 can be modified to become a true Web server using the GET command for HTTP 1 …

, Chapter: 3 -Problem: 19 >> In the discussion of ARQ protocol in Section 3.3.3, a scenario was outlined that resulted in the receiver accepting two copies of the same frame due to a loss of acknowledgement frame. Is it possible that a receiver may accept multiple copies of the same frame when none of the frames (message or acknowledgement) are lost?
Answer Preview: Yes it is possible The reason is that an acknowledgeme…

, Chapter: 2 -Problem: 41 >> The actual layout of cells is seldom as regular that as shown in Fig. 2-45. Even the shapes of individual cells are typically irregular. Give a possible reason why this might be. How do these irregular shapes affect frequency assignment to each cell? Figure 2-45 Transcribed Image Text: B B G G A D A
Answer Preview: First initial deployment simply placed cells in regions where there was a high density of human or v…

, Chapter: 6 -Problem: 5 >> In the Internet File Server example (Figure 6-6), can the connect( ) system call on the client fail for any reason other than listen queue being full on the server? Assume that the network is perfect. Figure 6-6 Transcribed Image Text: * This page contains a client program that can request a file fr
Answer Preview: The connect ma…

, Chapter: 8 -Problem: 44 >> Consider an image of 2048 × 512 pixels. You want to encrypt a file sized 2.5 MB. What fraction of the file can you encrypt in this image? What fraction would you be able to encrypt if you compressed the file to a quarter of its original size? Show your calculations.
Answer Preview: The image contains 2048 512 pixels Since each pixel contains 3 loworder bits the number of bits wh…

, Chapter: 7 -Problem: 18 >> IMAP allows users to fetch and download email from a remote mailbox. Does this mean that the internal format of mailboxes has to be standardized so any IMAP program on the client side can read the mailbox on any mail server? Discuss your answer.
Answer Preview: No The IMAP program does not actually touch the remote mailbox It sends c…

, Chapter: 8 -Problem: 45 >> The image of Fig. 8-54(b) contains the ASCII text of five plays by Shakespeare. Would it be possible to hide music among the zebras  instead of text? If so, how would it work and how much could you hide in this picture? If not, why not? Figure 8-54(b) Transcribed Image Text: (b)
Answer Preview: Easy Music is just a file It does not …

, Chapter: 2 -Problem: 22 >> A modem constellation diagram similar to Fig. 2-23 has data points at the following coordinates: (1, 1), (1, ˆ’1), (ˆ’1, 1), and (ˆ’1, ˆ’1). How many bps can a modem with these parameters achieve at 1200 symbols/second? Figure 2-23 Transcribed Image Text: 90 90 90 180 - 180 270 270 270 (b) (a) (c)
Answer Preview: There are four legal v…

, Chapter: 2 -Problem: 20 >> Is an oil pipeline a simplex system, a half-duplex system, a full-duplex system, or none of the above? What about a river or a walkie-talkie-style communication?
Answer Preview: Like a single railroad track it is half dup…

, Chapter: 6 -Problem: 2 >> Primitives of transport service assume asymmetry between the two end points during connection establishment, one end (server) executes LISTEN while the other end (client) executes CONNECT. However, in peer to peer applications such file sharing systems, e.g. BitTorrent, all end points are peers. There is no server or client functionality. How can transport service primitives may be used to build s
Answer Preview: Since the two end points are peers a separate applicationlevel mechanism is n…

, Chapter: 3 -Problem: 4 >> What is the maximum overhead in byte-stuffing algorithm?
Answer Preview: The maximum overhead occ…

, Chapter: 4 -Problem: 30 >> What is the maximum size of the data field for a 3-slot Bluetooth frame at basic rate? Explain your answer.
Answer Preview: A Bluetooth frame has an overhead of 126 bits for access code and header and a settlin…

, Chapter: 3 -Problem: 28 >> In the previous problem, suppose a sliding window protocol is used instead. For what send window size will the link utilization be 100%? You may ignore the protocol processing times at the sender and the receiver. Data From Previous Problem The distance from earth to a distant planet is approximately 9 × 1010 m. What is the channel utilization if a stop-and-wait protocol is used for frame transmis
Answer Preview: For a send window …

, Chapter: 5 -Problem: 29 >> While IP addresses are tried to specific networks, Ethernet addresses are not. Can you think of a good reason why they are not?
Answer Preview: Each Ethernet adapter sold in stores comes hardwired with an Ethernet MAC addres…

, Chapter: 1 -Problem: 28 >> Suppose there is a change in the service (set of operations) provided by layer k. How does this impact services at layers k-1 and k+1?
Answer Preview: There is no imp…

, Chapter: 2 -Problem: 31 >> SONET clocks have a drift rate of about 1 part in 109. How long does it take for the drift to equal the width of 1 bit? Do you see any practical implications of this calculation? If so, what?
Answer Preview: A drift rate of 10 9 means 1 second in 109 seconds or 1 nsec per second At O…

, Chapter: 8 -Problem: 49 >> Search the Internet for some court case involving copyright versus fair use and write a 1-page report summarizing your findings.
Answer Preview: CASES INVOLVING TEXT:- 1. FAIR USE:- Publisher Larry Flynt made disparaging statements about the Rev…

, Chapter: 7 -Problem: 27 >> (a) Consider the following HTML tag:

HEADER 1

Under what conditions does the browser use the TITLE attribute, and how?(b) How does the TITLE attribute differ from the ALT attribute?
Answer Preview: a The browser uses the TITLE attribute when a user hov…

, Chapter: 1 -Problem: 31 >> Make a list of activities that you do every day in which computer networks are used. How would your life be altered if these networks were suddenly switched off?
Answer Preview: A Computer Network is a network of resource sharing,which must have sender,medium and receive…

, Chapter: 3 -Problem: 39 >> The goal of this lab exercise is to implement an error-detection mechanism using the standard CRC algorithm described in the text. Write two programs, generator and verifier. The generator program reads from standard input a line of ASCII text containing an n-bit message consisting of a string of 0s and 1s. The second line is the kbit polynomial, also in ASCII. It outputs to standard output a line
Answer Preview: Total answers posted by the expert is: 118 #incl…

, Chapter: 7 -Problem: 47 >> Numerous people have registered DNS names that consist of www.word.com, where word is a common word. For each of the following categories, list five such Web sites and briefly summarize what it is (e.g., www.stomach.com belongs to a gastroenterologist on Long Island). Here is the list of categories: animals, foods, household objects, and body parts. For the last category, please stick to body part
Answer Preview: Animals www dog com ( selling supplies for pets) www cat com ( seling equ…

, Chapter: 6 -Problem: 21 >> Consider two networks, N1 and N2, that have the same average delay between a source A and a destination D. In N1, the delay experienced by different packets is unformly distributed with maximum delay being 10 seconds, while in N2, 99% of the packets experience less than one second delay with no limit on maximum delay. Discuss how RTP may be used in these two cases to transmit live audio/video stre
Answer Preview: In N since the maximum delay is 10 seconds an appropriate buffer ca…

, Chapter: 1 -Problem: 4 >> Besides bandwidth and latency, what other parameter is needed to give a good characterization of the quality of service offered by a network used for (i) Digitized voice traffic? (ii) Video traffic? (iii) Financial transaction traffic?
Answer Preview: A uniform delivery time is needed for voice as well as video so the amoun…

, Chapter: 7 -Problem: 13 >> Suppose that you want to send an MP3 file to a friend, but your friend’s ISP limits the size of each incoming message to 1 MB and the MP3 file is 4 MB. Is there a way to handle this situation by using RFC 5322 and MIME?
Answer Preview: Yes Use the messagee…

, Chapter: 2 -Problem: 8 >> It is desired to send a sequence of computer screen images over an optical fiber. The screen is 2560 × 1600 pixels, each pixel being 24 bits. There are 60 screen images per second. How much bandwidth is needed, and how many microns of wavelength are needed for this band at 1.30 microns?
Answer Preview: The data

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