Computer networks miscellaneous
- A sender uses the Stop-and-Wait ARQ protocol for reliable transmission of frames. Frames are of size 1000 bytes and the transmission rate at the sender is 80 Kbps (1Kbps = 1000 bits/second). Size of an acknowledgement is 100 bytes and the transmission rate at the receiver is 8Kbps. The one-way propagation delay is100 milliseconds. Assuming no frame is lost, the sender throughput is ________ bytes/second.
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2500
Frame size (L) = 1000 bytes
Sender side Bandwidth (Bs) = 80 kbps
Acknowledgement (LA) = 100 bytes
Receiver side Bandwidth (BR) = 8kbps
Tp = 100 msn = Tx Tx + Tack + 2Tp Tx(msg) = L = 1000 Bytes = 100 ms Bs 10 × 103 BPS TA(Ack) = LA = 100 Bytes = 100 ms BR 1 × 103 BPS
Tp = 100 ms∴ Channel Utilization = Tx = 100 ms = 1 Tx + Tack + 2Tp 100 ms + 100 ms + 200 ms 4 ∴ Throughput = η × B = 1 × 10 × 103 = 2.5 Kbps (or 2500 bps) 4 Correct Option: B
2500
Frame size (L) = 1000 bytes
Sender side Bandwidth (Bs) = 80 kbps
Acknowledgement (LA) = 100 bytes
Receiver side Bandwidth (BR) = 8kbps
Tp = 100 msn = Tx Tx + Tack + 2Tp Tx(msg) = L = 1000 Bytes = 100 ms Bs 10 × 103 BPS TA(Ack) = LA = 100 Bytes = 100 ms BR 1 × 103 BPS
Tp = 100 ms∴ Channel Utilization = Tx = 100 ms = 1 Tx + Tack + 2Tp 100 ms + 100 ms + 200 ms 4 ∴ Throughput = η × B = 1 × 10 × 103 = 2.5 Kbps (or 2500 bps) 4
- Which of the following is/are example(s) of stateful application layer protocols?
(i) HTTP (ii) FTP (iii) TCP (iv) POP3
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TCP is stateful as it maintains connection information across multiple transfers, but TCP is not an application layer protocol. Of the given protocols, only FTP and POP3 are stateful application layer protocols.
Correct Option: C
TCP is stateful as it maintains connection information across multiple transfers, but TCP is not an application layer protocol. Of the given protocols, only FTP and POP3 are stateful application layer protocols.
- Which one of the following protocols is NOT used to resolve one form of address to another one?
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DHCP is not used to resolve one form of address to another. DHCP is used to assign IP dynamically. All others are used to convert one address to other.
Correct Option: C
DHCP is not used to resolve one form of address to another. DHCP is used to assign IP dynamically. All others are used to convert one address to other.
- Which of the following is not true with respect to a transparent bridge and a router?
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Bridge is the device which work at data link layer whereas router works at network layer. Both selectively forward packets, build routing table & connect between LAN & WAN but since bridge works at data link it uses MAC addresses to route whereas router uses IP addresses. Application Layer Protocols
Correct Option: B
Bridge is the device which work at data link layer whereas router works at network layer. Both selectively forward packets, build routing table & connect between LAN & WAN but since bridge works at data link it uses MAC addresses to route whereas router uses IP addresses. Application Layer Protocols
- Which of the following system calls results in the sending of SYN packets?
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The 3 way handshake is shown as below
Host A sends a TCP SYNchronize packet to Host B Host B receives A’s SYN Host B sends a SYNchronize-ACKnowledgement Host A receives B’s SYN-ACK Host A sends ACKnowledge Host B receives ACK. TCP connecting is (Established). SYNchronize and ACKnowledge messagess are indicated by a bit inside the TCP head of the segment. The handshake (TCP Handshaking) between sender and receiver is established by connect so that SYN packets could be sent.
TCP knows whether the network connection is opening, synchronizing or established by using the SYNchronize and ACKnowledge messages when establishing a network connection. When the communication between two computer ends, another 3-way communication is performed to tear down the TCP connection. This setup and teardown of a TCP connection is part of what qualifies TCP a reliable protocol.Correct Option: D
The 3 way handshake is shown as below
Host A sends a TCP SYNchronize packet to Host B Host B receives A’s SYN Host B sends a SYNchronize-ACKnowledgement Host A receives B’s SYN-ACK Host A sends ACKnowledge Host B receives ACK. TCP connecting is (Established). SYNchronize and ACKnowledge messagess are indicated by a bit inside the TCP head of the segment. The handshake (TCP Handshaking) between sender and receiver is established by connect so that SYN packets could be sent.
TCP knows whether the network connection is opening, synchronizing or established by using the SYNchronize and ACKnowledge messages when establishing a network connection. When the communication between two computer ends, another 3-way communication is performed to tear down the TCP connection. This setup and teardown of a TCP connection is part of what qualifies TCP a reliable protocol.
