Computer Networks for GATE

Computer Networks marks come almost entirely from arithmetic, and the single largest cause of lost marks is merging transmission delay with propagation delay, which are independent quantities. Once the four delay components are kept separate, the store-and-forward pipelining formula and the bandwidth-delay product follow directly. Data link layer questions are dominated by sliding window efficiency, which is entirely a function of the propagation-to-transmission ratio, plus the CSMA/CD minimum frame size derivation. Network layer questions are subnetting, CIDR aggregation, longest prefix match and fragment offsets, all mechanical. Transport layer questions are congestion window traces, where the threshold must be updated explicitly at every loss event, and the application layer contributes DNS message counts and HTTP round-trip comparisons.