In a class C subnet of 255.255.255.240 are not host xxx.xxx.xxx.001 to xxx.xxx.xxx.15 invalid? Arnt the first eligable hosts xxx.xxx.xxx.017/28 to xxx.xxx.xxx.030/28?
thanks Steve C.
Subnetting Question
Feb 07, 2005
5 Replies
That depends upon whether you are running classful or classless routing. If running classless, it also depends upon whether or not you have the 'ip subnet-zero' option enabled. If running classful, not.
Also, with that subnet mask, .15 would be a broadcast address and cannot be used for a host address.
Fred
So, if I were running Rip V2, EIGRP or OSPF, I could have a 198.142.26.2/28 address?
Steve, great question. If you are studying for the Cisco CCNA exam, then yes, they are now valid. Pre- 2005 exams would have considered those invalid. As the other posts mention, this is the ip subnet-zero command, which is on by default starting in IOS version 12.1. Cheers! Todd Lammle
Yes, if the ip subnet-zero feature was enabled.
Type it at the global configuration prompt.
Fred
And that is why I check this news group every day! THANKS ALL. Now back to the books.
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