Download Networking questions

Possible test questions in Networking
On networking gadgets and network addresses
1. What is the role of a router in a computer network? How does it differ from a bridge? How does
a bridge differ from a repeater?
2. Discuss the difference between a network hub and a repeater. At what levels are they
employed?
3. What is DHCP for? In what ways does a DHCP server communicate with a PC client when it is
powered up? Indicate possible security related issues with DHCP servers.
4. A DNS server is employed to provide a mapping of a user supplied address to its IP address. How
does it handle addresses not available in its table?
5. A network on the Internet has a subnet mask of 255.255.240.0. What is the maximum number
of hosts it can handle?
6. A large number of IP addresses are available starting at an address 198.16.0.0. Suppose that four
organizations A, B, C and D request 4000, 2000, 4000, and 8000 addresses, respectively, and in
that order. For each of these, give the first IP address assigned, the last IP address assigned, and
the mask in w.x.y.z/d notation.
On Protocols
1. What are the advantages of layered protocols? What are its disadvantages?
2. Give two reasons for using layered protocols.
3. Imagine that you have trained your St. Bernard, Bernie to carry a box of three tapes instead of
brandy. These tapes each contain 10 GB of data. The dog can run at a speed of 30 km/hour. For
what range of distances does Bernie have a higher data rate than a 300 Mbps cable?
4. What does negotiation mean when discussing network protocols? Give an example.
5. Which of the OSI layers handle each of the following?
a. Dividing the transmitted bit stream into frames.
b. Determining which route through the subnet to use
6. What is the main difference between the TCP and the UDP?
7. What is the difference among a segment, a packet and a frame? At what levels are they
meaningful?
On LAN related questions
1. What is a LAN network? How does it differ from a MAN network? One could suggest that an
alternative to a LAN network is a large time-sharing system supporting a set of multiple
terminals under a single server. Would it be a valid statement to make? Why, or why not?
2. What are the differences among a LAN, a MAN and a WAN? Which one does constitute the
framework for the Internet? In what way is Internet different from an internet? In what ways
are they similar?
3. What is the difference between an ALOHA protocol and a slotted-ALOHA protocol? What is the
minimum amount of time one needs to wait in these two protocols, respectively? If you must
4.
5.
6.
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8.
9.
choose one of them to transmit your messages using a packet radio, which one would be the
preferred choice under (a) light traffic, and (b) under heavy traffic? Rationalize your answer.
Suppose the offered load density 𝐺 in an ALOHA communication system is 0.6 frames/sec. What
is the expected throughput in this case? Compute the same for a slotted ALOHA system.
How does efficiency of a CSMA/CD based LAN stand up as a function of cable bandwidth, cable
length and frame size? If the length of a LAN segment is increased by 10 folds, how does its
efficiency change?
Station A wants to communicate with B who happens to be some 8000 km away from A.
Suppose the effective bandwidth of the cable between the two is 10 Mb/sec. A wants to send a
file of size 5kb. After B receives the file, it sends a one-bit acknowledgment back to A. How long
would A take to transmit the file? How long does A need to wait to receive the
acknowledgement from B?
What is the difference between a contention-based LAN and a contention-free LAN? Under
what circumstances is one favored over the other? What is TDMA based LAN? How does it differ
from an FDMA based LAN? Are these contention-free LANs? State your reasons.
What is the hidden terminal problem? How is it handled?
What is the difference between a connectionless and connection-oriented network? What are
the advantages and disadvantages of these two modes of networking? From security point of
view, which one is potentially safer than the other? How is Voice over IP classified in terms of
these two? State your rationale.
On switched networks
1. A packet sent out by a host station may get lost, may be received corrupted or may even arrive
at a wrong address. Discuss how and under what circumstances these events may occur.
2. Besides bandwidth and latency (delay) what other parameter is needed to give a good
characterization of the quality of service offered by a network used for digitized voice traffic?
3. A client-server system uses a satellite network, with the satellite at a height of 40,000 km. What
is the best case delay in response to a request?
4. Wireless networks are easy to install, which makes them inexpensive since installation costs
usually far overshadow equipment costs. Nevertheless, they also have some disadvantages.
Name two of them.
5. An attempt was made to figure out how many hops (and time) it’d take to send a packet to
Prenticehall.com from SUNYIT. The following table shows the result. Outline what you can
surmise.
sengupta@fang:~>traceroute prenticehall.com
traceroute to prenticehall.com (165.193.215.183), 64 hops max, 52 byte packets
1 cs-out (150.156.192.1) 1.430 ms 0.839 ms 1.060 ms
2 nkr-c015-3845.sunyit.edu (192.52.220.2) 1.753 ms 1.764 ms 1.896 ms
3 ag-sunyitte-serial3-3-0.rocny01.paetec.net (74.8.226.209) 5.410 ms 4.792 ms 6.623 ms
4 ge-2-0-2-13.rochny01h07cr01.paetec.net (66.155.216.212) 48.689 ms 100.128 ms 86.663
ms
5 so-1-1-0.albynywbh38cr01.paetec.net (169.130.80.238) 15.438 ms 14.986 ms 15.536 ms
6 169.130.82.124 (169.130.82.124) 17.755 ms 15.017 ms 16.165 ms
7 146.82.34.141 (146.82.34.141) 56.037 ms 65.252 ms 52.485 ms
8 ae7-70G.scr4.NYC1.gblx.net (67.16.142.53) 53.035 ms 51.899 ms 52.826 ms
9 po2-10G.ar8.NYC1.gblx.net (67.16.137.98) 51.823 ms
te4-3-10G.ar8.NYC1.gblx.net (67.16.143.26) 51.608 ms
po1-20G.ar8.NYC1.gblx.net (67.16.137.94) 53.442 ms
10 er2-te-8-1.NewYork.savvis.net (166.63.146.37) 29.487 ms 29.156 ms 30.779 ms
11 cr1-tengig-0-8-3-0.NewYork.savvis.net (204.70.198.13) 31.091 ms 29.474 ms 28.892 ms
12 hr1-te-8-1-0.NewJerseynj2.savvis.net (204.70.197.14) 31.180 ms 29.481 ms 29.628 ms
13 hr1-ten-1-0-0.newjerseynj3.savvis.net (204.70.197.146) 31.596 ms 30.130 ms 30.250 ms
14 das2-v3009.nj3.savvis.net (64.14.170.66) 31.546 ms 31.136 ms 30.363 ms
15 * *
*
16 *^C
sengupta@fang:~>
6. Assuming that all routers and hosts are working properly and that all software in both is free of
all errors, is there any chance, however small, that a packet will be delivered to a wrong
destination?