Hierarchical addressing network addressing scheme?

hassantalal785

I have enough concept about hierarchical addressing network addressing scheme and what i don't understand is this question i read somewhere :

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

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


Answer: A E (As provided by the site)

I think answer should be C,E . "C" because out of 48 bits i.e 4 octets , 2 octets are used OUI so that enough bit sare used as OUI and enough(half) as NIC specific . Kindly explain as i think i am wrong .

Forsaken_GA

hassantalal785 wrote: »

I have enough concept about hierarchical addressing network addressing scheme and what i don't understand is this question i read somewhere :

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

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


Answer: A E (As provided by the site)

I think answer should be C,E . "C" because out of 48 bits i.e 4 octets , 2 octets are used OUI so that enough bit sare used as OUI and enough(half) as NIC specific . Kindly explain as i think i am wrong .

In an IP world C is blatantly wrong. MAC addresses are burned in at the factory, the administrator doesn't set them. As well, MAC's aren't used in IP routing, they're used for link local communication within a network segment at layer 2.

A is correct because if your scheme is hierarchical, you can summarize the routes. Ie, if one router has routes for 192.168.0.0/24, 192.168.1.0/24, 192.168.2.0/24 and 192.168.3.0/24, they can summarize it as 192.168.0.0/22 to all upstream neighbors, only needing to pass one route instead of 4. This is especially important for global internet routing, as the BGP table is quite large.

B is layer 1 function, doesn't involve addressing at all.

D. is likewise pointless and has more to do with link-local communication than network wide communication. Every device having dedicated links to every other device is cost prohibitive, so a good network scheme is irrelevant.

E is also correct. Having a good network scheme, like say these contiguous subnets are assigned to this site... if there's a problem with those addresses, then I immediately know which site is likely to be having issues, and that reduces troubleshooting and remediation time. Likewise, it would be easy to craft, say, ACL's to restrict or allow traffic to a site. In the same concept of route summarization to reduce routing table size, a good network scheme would allow me to write ACL statements that apply to an entire site with fewer lines, which reduces network complexity and management.