CCNA and IP Subnet 0

I recall these days Cisco routers come with IP subnet zero as default, so I would say your are correct saying 8

Am taking my CCNA tomorrow also got 837 Last week, good luck.

Cheers - u too!

Cisco Press offers this hint on which way to go:

Number of Subnets: Subtract 2, or Not?

When choosing a subnet mask, the mask value implies the number of host bits and the number of subnet bits. For host bits, the number of valid hosts per subnet is found using the formula 2n - 2, where n is the number of host bits. That formula is always true. To find the number of possible subnets, however, one of two formulas can be used, depending on a couple of factors. Choosing which formula to use can be tricky, and in part depends on the context and wording of the exam question. In short, if the question states or implies that classfull logic is needed, the formula should be 2n - 2, where n is the number of subnet bits. If the question implies the classless logic is needed, the formula is 2n.

Classful protocols (use 2n - 2): RIP v1 or IGRP SLSM (not VLSM)

Classless protocols (use 2n): OSPF, EIGRP, RIP v2 VLSM

Cisco makes no public statement about which to use if there are no hints in the question. In my humble opinion, if the question implies nothing at all about which formula to use, use 2n - 2. (Table 14-2 in Chapter 14, "Introduction to Dynamic Routing Protocols," introduces the concept of classless and classfull routing protocols. The ICND Exam Certification Guide covers more details about the differences.)

Thanks for that - that does more or less answer the question I had. Pleased to say though that I passed with a score of 925, next up CCNP... :-)

Well done, so did I 895 :)