1. We have two hosts A and B that are using sliding window protocol for flow control, and to transfer data from A to B full duplex link is used. The send window size and receive window size is 5 packets each. Data packets that are sent only from A to B are all 1000byte long and the transmission time for such a packet is 50µs. Acknowledgement packets that are sent only from B to A are very small and it requires negligible transmission time. In this communication the maximum achievable throughput, if the propagation delay over the link is 200µs, is
Answer is : 11.11 x 10^6 bps
2. The different activities pertaining to email are:
a. Send an email from a mail client to mail server.
b. Download an email from mailbox server to a mail client.
c. Checking email in a web browser.
In each activity given above, the application level protocol used, is
a. Send an email from a mail client to mail server.
b. Download an email from mailbox server to a mail client.
c. Checking email in a web browser.
In each activity given above, the application level protocol used, is
Answer is : a: SMTP, b: POP, c: HTTP
3. Which one of the following statement does not hold true about Internet protocol (IP)?
Answer is : A computer can have multiple IP address
4. Let computer A and computer B that have the IP addresses 10.105.1.113 and 10.105.1.91 respectively use the same net mask N. For A and B to belong to same network, the value of N should not be
Answer is : 255.255.255.224
For questions 5 and 6 refer to the data given below:
Let A, B and C be the three IP networks and Ha, Hb and Hc be the hosts of network A, network B and network c respectively. Message containing 180byte of application data is send by host Ha to host Hc through an intermediate network B. The TCP layer prefixes a 20byte header to the message. In each network, the maximum packet size including 20byte IP header is A: 1000byte, B: 100byte, C: 1000byte. The network A is connected to network B through a 1Mbps link and network B is connected to network C through a 512kbps link, where bps stands for bits per second.
5. Consider the packets are correctly delivered. In the best case, how many bytes including headers are delivered to the IP layer at the destination, for one application message? Consider only data packets.
Let A, B and C be the three IP networks and Ha, Hb and Hc be the hosts of network A, network B and network c respectively. Message containing 180byte of application data is send by host Ha to host Hc through an intermediate network B. The TCP layer prefixes a 20byte header to the message. In each network, the maximum packet size including 20byte IP header is A: 1000byte, B: 100byte, C: 1000byte. The network A is connected to network B through a 1Mbps link and network B is connected to network C through a 512kbps link, where bps stands for bits per second.
5. Consider the packets are correctly delivered. In the best case, how many bytes including headers are delivered to the IP layer at the destination, for one application message? Consider only data packets.
Answer is : 260
6. Neglecting errors, acknowledgements and other overheads, the rate at which application data is transferred to host Hc, is
Answer is : 354.5kbps
7. For real time multimedia, file transfer, DNS and email, the transport layer protocols used are respectively
Answer is : UDP, TCP, UDP and TCP
8. A device that can look at all protocol headers up to the transport layer is called l ayer-4 firewall. Which one of the following statement is true layer-4 firewall?
Answer is : It cannot block TCP traffic from a specific user on a multi-user system during 9:00pm and 5:00am
9. The source and destination are connected through two intermediate routers. During the data transmission from source to destination how many times each packet has to visit the network layer and the data link layer?
Answer is : Network layer – 4 times and data link layer – 6 times
10. (11) For the application layer in the Internet stack, the protocol data unit (PDU) is
Answer is : Message
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