CISCO CCNA Exam – Q147

Which two benefits are provided by using a hierarchical addressing network addressing scheme? (Choose two.)

A. reduces routing table entries
B. auto-negotiation of media rates
C. efficient utilization of MAC addresses
D. dedicated communications between devices
E. ease of management and troubleshooting

Correct Answers: A,E

Here are some of the benefits of hierarchical addressing:

Reduced number of routing table entries — whether it is with your Internet routers or your internal routers, you should try to keep your routing tables as small as possible by using route summarization. Route summarization is a way of having a single IP address represent a collection of IP addresses; this is most easily accomplished when you employ a hierarchical addressing plan. By summarizing routes, you can keep your routing table entries (on the routers that receive the summarized routes) manageable, which offers the following benefits:

  • More efficient routing
  • A reduced number of CPU cycles when recalculating a routing table or sorting through the routing table entries to find a match
  • Reduced router memory requirements
  • Reduced bandwidth required to send the fewer, smaller routing updates
  • Faster convergence after a change in the network
  • Easier troubleshooting
  • Increased network stability

Efficient allocation of addresses — Hierarchical addressing lets you take advantage of all possible addresses because you group them contiguously.