3i Infotech Placement: Sample Questions 410 - 411 of 1245

Glide to success with Doorsteptutor material for competitive exams : get questions, notes, tests, video lectures and more- for all subjects of your exam.

Question 410

Edit

Describe in Detail

Essay▾

What is the translation look aside Buffer?

Explanation

Understanding of Translation Look-Aside Buffers
  • Every time the CPU accesses virtual memory, a virtual address translated to the corresponding physical address.
  • Page table contains translations from virtual address to physical address.
  • TLB is a hardware cache that stores recent translation of virtual memory to physical addresses for faster retrieval- part of the chip՚s memory management unit.
  • TLB can reside between the CPU and the CPU cache, between CPU cache and the main memory or between different levels of the multi-level cache.
  • Present inside memory management hardware- in processor that utilizes paged or segment virtual memory.
  • Without TLB every virtual memory reference will cause 2 physical memory accesses one to fetch appropriate page table entry, and fetch the desired data.

Cache Thrash

  • Transaction look aside buffer suffers performance issues from multitasking and code errors.
  • Performance degradation is called a cache thrash.

Question 411

Edit

Describe in Detail

Essay▾

What is OSPF?

Explanation

OSPF Autonomous System
  • Stands for Open Shortest Path First.
  • A routing protocol for internet protocol.
  • Used a link state routing algorithm and falls into the group of interior gateway protocols, operating within a single autonomous system.
  • Outing protocol has largely replaced the older Routing Information Protocol in corporate networks.
  • Link-state routing protocol means that the routers exchange topology information with their nearest neighbour.
  • Calculates end-to-end paths through the autonomous system using a variant of the Dijkstra algorithm.

Working of OSPF

  • OSPF network works based on area and autonomy.
  • OSPF network divided into groups called areas- OSPF is based on functional areas like a building or the floor of a building.
  • Autonomous systems (AS) are collections of areas- for example, every router in an organization cab probably be part of a single AS. These regions are automatically configured and routed by the router.

Advantages:

  • A link state routing protocol like OSPF provides complete knowledge of topology allowing routers to calculate routes satisfying particular criteria- shortest distance, least cost, least time, best QoS etc.
  • For traffic engineering purpose, route can be constrained to meet particular quality of service.

Disadvantages:

  • Link state routing protocol does not scale well with more routers in the routing domain.
  • Number of routers increases the size and frequency of the topology updates, and time taken to calculate routes.

Developed by: