CPE 400

How many bits are used by IPV6 for source or destination IP address?

b) 128 bits

If the ACK value is 200, then byte _______ has been received successfully.

b) 199

TCP segment has mandatory ________________ bytes long header.

b) 20

How many bytes of mandatory header is used in IPV4 datagram?

b) 20 bytes

1. What is the size of the sequence number field in TCP segment structure?

b) 32 bits

If a packet size is 2500 bits and the rate at which a router can pump out packets is 5 Mega bits per second, then the transmission delay in milliseconds is:

b) 500 microseconds

By default, what type of query does nslookup do for a domain?

b) A

Your home network router address is 192.168.2.1. Which class is this IP address in?

b) C

Which of the following 5 components must be part of reliable data transfer protocol?

b) Checksum, Timer, Sequence number, Acknowledgement and Pipelining

Which route computation algorithm is used by OSPF routing mechanism?

b) Dijkstra

In DSR, when node S wants to send a packet to node D, but does not know a route to D, node S initiates a route discovery using message

b) RREQ

The transport layer protocol serving HTTP for web browsing is

b) TCP

What does the phrase non-authoritative answer in the nslookup output mean?

b) The information in the output was obtained from a server cache

Multicasting communication is

b) When a packet is sent from a single source to multiple destinations

What is NOT true about persistent HTTP connection?

b) downloading multiple objects must require multiple TCP connections

Ethernet is a ________________________ protocol.

b. Random access

What are the leading bits in a class C IP address?

c) 110

If a packet size is 1500 bits and the rate at which a router can pump out packets is 10Mega bits per second, then the transmission delay is:

c) 150 microseconds

How many bits are used for AS number field?

c) 16 bits

DNS databases contain

c) 53

DNS server uses port

c) 53

In TCP, the size of the transmission window is the ________ of rwnd and cwnd.

c) Minimum

The time required to examine the packet's header and determine where to direct the packet is part of

c) Nodal Processing delay

1. For the following event at receiver, what would be TCP receiver's action? Event: arrival of out-of-order segment higher-than-expect seq. # . Gap detected.

c) Send duplicate ACK, indicating seq. # of next expected byte.

In modern implementations of TCP, a retransmission occurs if the retransmission timer expires or ________ duplicate ACK segments have arrived.

c) Three

1. Which one of the following protocol delivers/stores mail to receiver server?

c) simple mail transfer protocol

Which one of the following is NOT part of the network protocol stack?

c) synchronization layer

Gigabit Ethernet has a data rate of ________Mbps.

c. 1000

How many bits are there in a MAC address?

c. 48 bits

In Ethernet, 1 slot is equivalent to _________bit times.

c. 512

Assume a client is establishing communication with a server through a 3-way TCP handshake protocol. In this connection establishment phase, when the server is responding, which of the six flags (U, A, P, R, S, F) will be set by the server?

c. A and S

ARP requests and ARP replies are done using _________ and _________ communication mechanism.

c. Broadcasting; unicasting

A spanning tree is a graph in which there is no _____.

c. Cycle

DSR algorithm is an example of

d) Reactive Decentralized routing algorithm

Application layer protocol defines:

d) all of the above

The special IP address 127.0.0.1 is used for _______ purpose.

d) loopback

Bluetooth is an example of

d) none of the above

NAT is controversial because

d)Routers should only process up to layer 3 but NAT routers process up to layer 4

Which protocol helps us in resolving MAC address given the host's IP address?

d. ARP

Why is web-cache needed?

reduces traffic on an institution's access link reduces response time for client request reduces load at the server, particularly for the static contents enables content providers to effectively deliver content

Transport layer decapsulates data from _______________

a) network layer

In the congestion detection algorithm, if detection is by a time-out, a new _______ phase starts.

a) slow start

Which one is a locally administered MAC address? (Hint: second least significant bit in most significant byte is set to 1 in locally administered address)

a. 1A-2F-BB-76-09-AD

Which protocol helps us in managing multicast groups?

a. IGMP

1 GBps is equivalent to

8 Gbps

For an IP address 191.54.38.207 with netmask 255.255.0.0 and subnet mask 255.255.255.224 what is the number of hosts per subnet?

So, host part is 5 bits Total hosts = 2^5 -2 = 30 30 hosts

What is the difference between TCP congestion control and flow control?

TCP congestion control makes sure the network bandwidth/capacity is not overwhelmed by the sender's transmission rate while TCP flow control makes sure the receiver buffer is not overwhelmed by the sender's transmission rate.

Which protocol helps us in managing multicasting

UDP

ARP protocol works at __________ layer.

network layer

1GB/S data rate is equivalent to

1000 Mb/S

Explain why Wi-Fi protocol cannot use CSMA/CD.

A wireless antenna (technically speaking transceiver) cannot send and receive at the same time. It seems like you are doing both at one time but that's thanks to the speed factor (switching between TX and RX rapidly). Signal as well

6. [3] What are the differences between TCP Congestion control and TCP flow control?

Congestion control is a method of ensuring that every TCP transmitter is accessing the network in a "fair" way without congesting or overwhelming the network links flow control is a method of ensuring that every TCP transmitter is transmitting in a "fair" way without congesting or overwhelming the TCP receivers' buffer

A. You want to implement a mechanism that automates the IP configuration, including IP address, subnet mask, default gateway, and DNS information. Which protocol will you use to accomplish this?

DHCP

Why do HTTP, SMTP and FTP require TCP as underneath transport layer process while DNS uses UDP as underneath transport layer process?

HTTP, SMTP, FTP require reliable packet transfer service. They are NOT "so called best effort service". TCP provides that reliability through transmission/ACK and retransmissions. DNS is a best effort service protocol. As a result, DNS is satisfied with UDP. DNS requests have explicit responses in the application layer itself. So no other acknowledgement is necessary at transport layer.

What is the difference between iterative and recursive DNS query?

Iterative: Burden of name resolution on local DNS server Recursive: Burden of name resolution on contacted name server (either local or root or TLD or authoritative based on who is contacted)

For an IP address 191.54.38.207 with netmask 255.255.0.0 and subnet mask 255.255.255.224 what is the max total number of subnets?

Network part 16 bits Rest = 16 bits Out of that, subnet part = 11 bits So, host part is 5 bits Total subnets = 2^11 = 2048 2048 subnets

2. [2+1=3] What are the four components of delay in networking? Why does packet loss happen?

Nodal Processing, Queuing, Transmission and Propagation delay Router queue (aka buffer) has finite capacity. Packets arriving to full queue will be dropped resulting in packet loss. Packet loss can also happen due to link failure or node failure.

Why the protocol of reliability is introduced in layer 2 (link layer) in the network protocol stack even though it is already implemented in layer 4 (transport layer) through TCP? What is the significance of ARP protocol?

Reliability is exposed in end to end only, and will take a long amount of time for A->B to realize it has been successful. It will take much more time than if there are multiple routers or switches to detect failure. ARP discovers link layer address.

Which of the following is NOT a correct statement?

Routers examine packets at application layer.

What is wireshark in promiscuous mode?

Wireshark will pick up packets not meant for your computer, but only your subnet. Everthing must be near the collision domain.

What are the technical Implications of wireshark?

You can understand the packet format by using wireshark, giving a visual representation of what constitutes a packet, to determine payload, link layer, etc. Drawbacks are, due to it's nature, with malicious intent you can sniff packets. Legal implication is you can be exposed to someone else's data without you being aware that it was sensitive.

In the transfer of file between server and client over four hops (links), if the transmission rates along the path is 40Mbps, 30Mbps, 20Mbps, 10Mbps, the throughput of the connection between server and client is

a) 10Mbps

In the layer hierarchy as the data packet moves from the upper to the lower layers, headers are

a) Added

Which route computation algorithm is used by routing mechanism of RIP?

a) Bellman-Ford

TCP assigns a sequence number to each segment that is being sent. The sequence number for each segment is number of the __________ byte carried in that segment.

a) First

Link state routing algorithm is an example of

a) Proactive Centralized routing algorithm

A set of rules that governs data communication is known as

a) Protocols

User datagram protocol is called connectionless because

a) all UDP packets are treated independently by transport layer

The domain name system is maintained by

a) distributed database system

TCP assigns a sequence number to each segment that is being sent. The sequence number for each segment is number of the __________ byte carried in that segment.

a) first

Convert the IP address from binary to dotted decimal notation:

d) 127.255.255.255

In a class A IP address, how many bits are used for network part and how many bits are used for host part?

d) 8,24

In addition to assigning an IP address, what other information are provided by DHCP?

d) All of the above

Which of the following is NOT a function of application layer?

d) All of the above

Why is Ad hoc routing challenging?

d) All of the above