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$$\small{\overset{{\large{\textbf{Mark Distribution in Previous GATE}}}}{\begin{array}{|c|c|c|c|c|c|c|c|}\hline \textbf{Year}&\textbf{2019}&\textbf{2018}&\textbf{2017-1}&\textbf{2017-2}&\textbf{2016-1}&\textbf{2016-2}&\textbf{Minimum}&\textbf{Average}&\textbf{Maximum} \\\hline\textbf{1 Mark Count}&1&3&2&3&2&3&1&2.3&3 \\\hline\textbf{2 Marks Count}&4&2&3&1&4&3&1&2.8&4 \\\hline\textbf{Total Marks}&9&7&8&5&10&9&\bf{5}&\bf{8}&\bf{10}\\\hline \end{array}}}$$

# Questions without answers in Computer Networks

1
How will you send an e-mail to someone when you have neither the recipient's e-mail address nor the e-mail application.
1 vote
2
Consider Dijkstra's algorithm in linked state routing protocol at node $u.$ Professor Ram first sets the route for each directly connected node $v.$ to be the link connecting $u$ to $v.$ Ram then implements the rest of the algorithm correctly, aiming to produce minimum cost ... and link costs where all routing table entry will be correct. $D)$ Both $A)$ and $B)$ How Dijkstra working here?
1 vote
3
The data link layer uses a fixed-size sliding window protocol, where the window size for the connection is equal to twice the bandwidth-delay product of the network path. Consider the following three scenarios, in each of which only the given parameter changes as specified (no other ... the minimum value of the round trip time $R$ increases to $1.8R$; the window size $W$ decreases to $W/3$
4
5
Consider a very large network $10000$ routers. Two host $A$ and $B$ connected with this network. Host $A$ sends a data to host $B$. and after some unit of time host $A$ receives $ICMP$ time exceed message for the samedata packet. The number of router ... some distance some ICMP message generated? Say if $ICMP$ message generated in $9999th$ router, then where it give error of time exceed message?
6
Visit the Selective Repeat Java applet at the companion Web site. Have the source send five packets, and then pause the animation before any of the five packets reach the destination. Then kill the first packet and resume the animation. Describe what happens. Repeat ... . Describe again what happens. Finally, try sending six packets. What happens? How selective repeat and go back-n is different?
7
Suppose that the roundtrip delay between the sender and receiver is constant and known to the sender. Would a timer still be necessary for protocol rdt 3.0 as shown in the figure, assuming that packets can be lost? Explain.
8
Consider a planet where everyone belongs to a family of six, every family lives in its own house, each house has a unique address, and each person in a given house has a unique name. Suppose this planet has a mail service that delivers letters from source house ... member. In your protocol, does the mail service ever have to open the envelope and examine the letter in order to provide its service?
9
Suppose the network layer provides the following service. The network layer in the source host accepts a segment of maximum size 1,200 bytes and a destination host address from the transport layer. The network layer then guarantees to deliver the segment to the transport ... destination process. In your protocols, does the transport layer have to do anything in the core of the computer network?
10
Look over your received emails, and examine the header of a message sent from a user with a .edu email address. Is it possible to determine from the header the IP address of the host from which the message was sent? Do the same for a message sent from a Gmail account.
11
Print out the header of an e-mail message you have recently received. How many $Received:$ header lines are there? Analyze each of the header lines in the message.
12
Why is it said that FTP sends control information “out-of-band”?
13
Describe how Web caching can reduce the delay in receiving a requested object. Will Web caching reduce the delay for all objects requested by a user or for only some of the objects? Why?
14
What is meant by a handshaking protocol?
15
For a P2P file-sharing application, do you agree with the statement, “There is no notion of client and server sides of a communication session”? Why or why not?
16
What is the difference between network architecture and application architecture?
17
List five nonproprietary Internet applications and the application-layer protocols that they use.
18
Suppose two hosts, A and B, are separated by 20,000 kilometers and are connected by a direct link of R = 1Gbps. Suppose the propagation speed over the link is $2.5 10^8$ meters/sec Calculate the bandwidth-delay product, $R \times d _{prop}$. Consider sending a file of ... the maximum number of bits that will be in the link at any given time? What is the width (in meters) of a bit in the link?
19
Suppose two hosts, A and B, are separated by 20,000 kilometers and are connected by a direct link of R = 2 Mbps. Suppose the propagation speed over the link is 2.5×1082.5×108 meters/sec. suppose we can modify R. For what value of R is the width of a bit as long as the length of the link?
20
Suppose there is a 10 Mbps microwave link between a geostationary satellite and its base station on Earth. Every minute the satellite takes a digital photo and sends it to the base station. Assume a propagation speed of $2.4 \times 10^8$meters/sec. What is the ... ? Let x denote the size of the photo. What is the minimum value of x for the microwave link to be continuously transmitting?
21
.Suppose two hosts, A and B, are separated by 20,000 kilometers and are connected by a direct link of R = 2 Mbps. Suppose the propagation speed over the link is $2.5 \times 10^8$ meters/sec. Calculate the bandwidth-delay product, $R \times d _{prop}$. Consider ... a general expression for the width of a bit in terms of the propagation speed s, the transmission rate R, and the length of the link m.
22
Suppose N packets arrive simultaneously to a link at which no packets are currently being transmitted or queued. Each packet is of length L and the link has transmission rate R. What is the average queuing delay for the N packets? Now suppose that N such packets arrive to the link every LN/R seconds. What is the average queuing delay of a packet?
23
A packet switch receives a packet and determines the outbound link to which the packet should be forwarded. When the packet arrives, one other packet is halfway done being transmitted on this outbound link and four other packets are waiting to be transmitted. Packets are ... rate is R, x bits of the currently-being-transmitted packet have been transmitted, and n packets are already in the queue?
24
(Common data question P10, P11) P10. Consider a packet of length L which begins at end system A and travels over three links to a destination end system. These three links are connected by two packet switches. Let $d _i, s _i, and R _i$ denote the ... forward packets but instead immediately transmits each bit it receives before waiting for the entire packet to arrive. What is the end-to-end delay?
25
In the discussion of packet switching versus circuit switching with a 1 Mbps link. Users are generating data at a rate of 100 kbps when busy, but are busy generating data only with probability p = 0.1. Suppose that the 1 Mbps link is replaced by a 1 Gbps link. What is N ... user population of M users. Give a formula (in terms of p, M, N) for the probability that more than N users are sending data.
26
Suppose users share a 3 Mbps link. Also, suppose each user requires 150 kbps when transmitting, but each user transmits only 10 percent of the time. When circuit switching is used, how many users can be supported? For the remainder of this ... are transmitting simultaneously. (Hint: Use the binomial distribution.) Find the probability that there are 21 or more users transmitting simultaneously.
27
This elementary problem begins to explore propagation delay and transmission delay, two central concepts in data networking. Consider two hosts, A and B, connected by a single link of rate R bps. Suppose that the two hosts are separated by m meters, and suppose the propagation speed along the link is ... $d _{prop}$ equals $d _{trans}$.