GATE CS Computer Networks questions

Two hosts are connected via a packet switch with $10^7$ bits per second links. Each link has a propagation delay of $20$ microseconds. The switch begins forwarding a packet $35$ microseconds after it receives the same. If $10000$ bits of data are to be transmitted between the two hosts using a packet size of $5000$ bits, the time elapsed between …

Consider a network connecting two systems located $8000$ $\text{Km}$ apart. The bandwidth of the network is $500 \times 10^6$ $\text{bits}$ per second. The propagation speed of the media is $4 \times 10^6$ $\text{meters}$ per second. It needs to design a Go-Back-$N$ sliding window protocol for this network. The average packet size is $10^7$ …

Consider the following statements. TCP connections are full duplex TCP has no option for selective acknowledgement TCP connections are message streams

Consider a CSMA/CD network that transmits data at a rate of $100\;\textsf{Mbps}\; (10^8\;\text{bits}$ per second) over a $1\;\textsf{km}$ (kilometre) cable with no repeaters. If the minimum frame size required for this network is $1250\;\text{bytes},$ What is the signal speed $\textsf{(km/sec)}$ in the cable?

Consider a selective repeat sliding window protocol that uses a frame size of $1$ $\text{KB}$ to send data on a $1.5$ $\text{Mbps}$ link with a one-way latency of $50$ $\text{msec}$. To achieve a link utilization of $60\%$, the minimum number of bits required to represent the sequence number field is ________.

Let the size of congestion window of a TCP connection be $32$ KB when a timeout occurs. The round trip time of the connection is $100$ msec and the maximum segment size used is $2$ KB. The time taken (in msec) by the TCP connection to get back to $32$ KB congestion window is _________.

Consider a token ring network with a length of 2 km having 10 stations including a monitoring station. The propagation speed of the signal is $2 \times10^8m/s$ and the token transmission time is ignored. If each station is allowed to hold the token for $2 µsec$, the minimum time for which the monitoring station should wait (in $µsec$) before assuming …

Which of the following are used to generate a message digest by the network security protocols? RSA SHA-$1$ DES MD5

Consider the following three statements about link state and distance vector routing protocols, for a large network with $500$ network nodes and $4000$ links. [S1]: The computational overhead in link state protocols is higher than in distance vector protocols. [S2]: A distance vector protocol (with split horizon) avoids persistent routing loops, but not …

An IP machine $Q$ has a path to another $IP\ machine\ H$ via three $IP\ routers \ R1, R2,$ and $R3$. $Q-R1-R2-R3-H$ $H$ acts as an $\text{HTTP}\ server$, and $Q$ connects to $H$ via $\text{HTTP}$ and downloads a file. Session layer encryption is used, with $\text{DES}$ as the shared key encryption protocol. Consider the following four …

Consider the store and forward packet switched network given below. Assume that the bandwidth of each link is $10^6$ bytes / sec. A user on host $A$ sends a file of size $10^3$ bytes to host $B$ through routers $R1$ and $R2$ in three different ways. In the first case a single packet containing the complete file is transmitted from $A$ to $B$. …

In the diagram shown below, $L1$ is an Ethernet LAN and $L2$ is a Token-Ring LAN. An $IP$ packet originates from sender $S$ and traverses to $R$, as shown. The links within each $\text{ISP}$ and across the two $\text{ISP}$s, are all point-to-point optical links. The initial value of the $\text{TTL}$ field is $32$. The maximum possible value …

Which of the following socket API functions converts an unconnected active TCP socket into a passive socket?

Which of the following is TRUE about the interior gateway routing protocols $-$ Routing Information Protocol $(RIP)$ and Open Shortest Path First $(OSPF)$

An $IP$ router with a $\text{Maximum Transmission Unit (MTU)}$ of $1500$ bytes has received an $IP$ packet of size $4404\text{ bytes}$ with an $IP$ header of length $20\text{ bytes}$. The values of the relevant fields in the header of the third $IP$ fragment generated by the router for this packet are:

Every host in an $\textsf{IPv4}$ network has a $1\text{-second}$ resolution real-time clock with battery backup. Each host needs to generate up to $1000$ unique identifiers per second. Assume that each host has a globally unique $\textsf{IPv4}$ address. Design a $50\text{-bit}$ globally unique ID for this purpose. After what period (in seconds) …

An IP router implementing Classless Inter-domain Routing (CIDR) receives a packet with address $131.23.151.76$. The router's routing table has the following entries: …

Host A (on TCP/IP v4 network A) sends an IP datagram D to host B (also on TCP/IP v4 network B). Assume that no error occurred during the transmission of D. When D reaches B, which of the following IP header field(s) may be different from that of the original datagram D? TTL Checksum Fragment Offset

A bit-stuffing based framing protocol uses an $\text{8-bit}$ delimiter pattern of $01111110.$ If the output bit-string after stuffing is $01111100101,$ then the input bit-string is:

In the following pairs of OSI protocol layer/sub-layer and its functionality, the INCORRECT pair is