Hughes Papers: Sample Questions 6 - 8 of 19

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Question number: 6

» Basic CS » Networks

Short Answer Question▾

Write in Short

Which part of the IP header is used for the time limit of the packet?

Explanation

  • Time To Live (TTL) field relates number of hops that a packet is permitted to travel before being discarded by router. Once this time stamp is elapsed data is discarded from the computer networks.
  • In the internet protocol, TTL field is of 8 bits and its maximum value is 255. In IPv4 this is measured in seconds. Every host that passes the datagram must reduce the TTL field by one, which was previously set by the sender. Thus, it is renamed as ‘hop limit’ in case of IPv6 header.

Question number: 7

» Languages » Assembly Language

Short Answer Question▾

Write in Short

What is pipeline architecture?

Explanation

  • Pipeline architecture is used to increase the instruction throughput. A pipelined architecture processor will not wait for the result of previous operations; it fetches and starts to execute the next instruction. Here, the instruction cycle is broken up into a series called pipeline. These pipelines are executed in parallel and instructions concurrently.
  • Pipeline stages for RISC processors are,
  1. Instruction fetch
  2. Instruction decode and operand fetch
  3. Execute instruction
  4. Memory access
  5. Write back

Question number: 8

» Languages » Assembly Language

Short Answer Question▾

Write in Short

If the cache access time is 1 nano seconds and main memory access time is 2 nano seconds and hit ratio is 0.9, then calculate the average access time.

Explanation

Relation between average access time, hit ratio, cache access time and memory access time is,

Where, Tavg = average access time

h = hit ratio

1 - h = miss ratio

Tc = cache access time

Tm = memory access time

Substituting values in equation (i),

Average access time is 1.1 nano seconds.