Thursday, March 03, 2005

Notes from CCNA Class

I'll be leaving for my CCNA class shortly. Yesterday we discussed changes brought about by the introduction of the ip subnet-zero feature. This allows a subnet like 172.16.0.0/19 to be valid. According to Cisco:

"It should be noted that even though it was discouraged, the entire address space including subnet zero and the all-ones subnet have always been usable. The use of the all-ones subnet was explicitly allowed and the use of subnet zero is explicitly allowed since Cisco IOS Software Release 12.0. Even prior to Cisco IOS Software Release 12.0, subnet zero could be used by entering the ip subnet-zero global configuration command."

Apparently the CCNA objectives now recognize the use of subnet zero, and Cisco expect students to calculate hosts and subnets appropriately. Previous CCNA objectives did not recognize subnet zero.

I also learned that material on OSPF, previously found mainly in the CCNP exam, is now part of the CCNA objectives. This would seem to make the CCNA test more difficult. I am not overly concerned, since the CCNA objectives no longer force students to learn IPX, AppleTalk, and other seldom-seen protocols.

2 comments:

Alastair said...

re: subnet zero. This must have been a recent change in the CCNA curriculum (and an important one at that!) because even the Lammle book says "don't do it in the exam even though it's a legitimate technique and does work in real life".

My only gripe with the OSPF material is that it's very much pitched as a moderately-inferior version of EIGRP, to be used only if you require interoperability with other vendors. I'm not sure it's that simple...

Richard Bejtlich said...

It is apparently a recent change to the CCNA objectives. Todd's latest books say "IP subnet-zero is not a new command, but in the pre-2005 CCNA objectives, Cisco didn't cover it." Todd said the same thing in class. I guess that shows (1) it pays to read the lastest edition of a certification book; and (2) it pays to take a class that keeps pace with the certification.