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Networking Questions Set 77:

Quiz Mode

What is the data rate of the STS-1 level of electrical signaling in SONET?

51.84 Mbps

155.52 Mbps

2488.320 Mbps

622.080 Mbps

Solution:

Transmission delay does not depend on _____

Packet length

Distance between the routers

Transmission rate

Bandwidth of medium

Solution:

The function of a Digital Subscriber Line Access Multiplexer (DSLAM) is to __________

Convert analog signals into digital signals

Convert digital signals into analog signals

Amplify digital signals

De-amplify digital signals

Solution:

Consider the following statements about the routing protocols, Routing Information Protocol(RIP) and Open Shortest Path First(OSPF) in an IPv4 network.
I. RIP uses distance vector routing
II. RIP packets are sent using UDP
III. OSPF packets are sent using TCP
IV. OSPF operation is based on link-state routing
Which of the following above are CORRECT?

I and IV only

I, II and III only

I, II and IV only

II, III and IV only

Solution:

In an Ethernet local area network, which one of the following statements is TRUE?

A station stops to sense the channel once it starts transmitting a frame.

The purpose of the jamming signal is to pad the frames that are smaller than the minimum frame size.

A station continues to transmit the packet even after the collision is detected.

The exponential backoff mechanism reduces the probability of collision on retransmissions

Solution:

Host A sends a UDP datagram containing 8880 bytes of user data to host B over an Ethernet LAN. Ethernet frames may carry data up to 1500 bytes (i.e. MTU = 1500 bytes). Size of UDP header is 8 bytes and size of IP header is 20 bytes. There is no option field in IP header. How may total number of IP fragments will be transmitted and what will be the contents of offset field in the last fragment?

6 and 925

6 and 7400

7 and 1110

7 and 8880

Solution:

Consider a TCP connection between a client and a server with the following specifications; the round trip time is 6 ms, the size of the receiver advertised window is 50 KB, slow-start threshold at the client is 32 KB, and the maximum segment size is 2 KB. The connection is established at time t=0. Assume that there are no timeouts and errors during transmission. Then the size of the congestion window (in KB) at time t+60 ms after all acknowledgements are processed is

Solution:

An organization requires a range of IP address to assign one to each of its 1500 computers. The organization has approached an Internet Service Provider (ISP) for this task. The ISP uses CIDR and serves the requests from the available IP address space 202.61.0.0/17. The ISP wants to assign an address space to the organization which will minimize the number of routing entries in the ISP’s router using route aggregation. Which of the following address spaces are potential candidates from which the ISP can allot any one of the organization ?
I. 202.61.84.0 / 21 II. 202.61.104.0 / 21 III. 202.61.64.0 / 21 IV. 202.61.144.0 / 21

I and II only

II and III only

III and IV only

I and IV only

Solution:

Consider two hosts P and Q connected through a router R. The maximum transfer unit (MTU) value of the link between P and R is 1500 bytes, and between R and Q is 820 bytes. A TCP segment of size 1400 bytes was transferred from P to Q through R, with IP identification value as 0×1234. Assume that the IP header size is 20 bytes. Further, the packet is allowed to be fragmented, i.e., Don’t Fragment (DF) flag in the IP header is not set by P. Which of the following statements is/are correct?
Two fragments are created at R and the IP datagram size carrying the second fragment is 620 bytes.
If the second fragment is lost, R will resend the fragment with the IP identification value 0×1234.
If the second fragment is lost, P is required to resend the whole TCP segment.
TCP destination port can be determined by analysing only the second fragment.

2, 4

1, 3

2, 3

1, 4

Solution:

Consider a simple communication system where multiple nodes are connected by a shared broadcast medium (like Ethernet or wireless). The nodes in the system use the following carrier-sense the medium access protocol. A node that receives a packet to transmit will carrier-sense the medium for 5 units of time. If the node does not detect any other transmission in this duration, it starts transmitting its packet in the next time unit. If the node detects another transmission, it waits until this other transmission finishes, and then begins to carrier-sense for 5 time units again. Once they start to transmit, nodes do not perform any collision detection and continue transmission even if a collision occurs. All transmissions last for 20 units of time. Assume that the transmission signal travels at the speed of 10 meters per unit time in the medium. Assume that the system has two nodes P and Q, located at a distance d meters from each other. P starts transmitting a packet at time t = 0 after successfully completing its carrier-sense phase. Node Q has a packet to transmit at time t = 0 and begins to carrier-sense the medium. The maximum distance d (in meters, rounded to the closest integer) that allows Q to successfully avoid a collision between its proposed transmission and P’s on going transmission is

150

Networking Questions Set 77:

What is the data rate of the STS-1 level of electrical signaling in SONET?

Solution:

Transmission delay does not depend on _____

Solution:

The function of a Digital Subscriber Line Access Multiplexer (DSLAM) is to __________

Solution:

Solution:

In an Ethernet local area network, which one of the following statements is TRUE?

Solution:

Solution:

Solution:

Solution:

Solution:

Solution:

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