1. Home
  2. Cisco Certification
  3. Subnetting Question

Subnetting Question

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.

Reply to
Steve C
Loading thread data ...

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

Reply to
Fred Atkinson

So, if I were running Rip V2, EIGRP or OSPF, I could have a 198.142.26.2/28 address?

Reply to
Steve C

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

Reply to
Todd Lammle

Yes, if the ip subnet-zero feature was enabled.

Type it at the global configuration prompt.

Fred

Reply to
Fred Atkinson

And that is why I check this news group every day! THANKS ALL. Now back to the books.

Reply to
Steve C

Cabling-Design.com Forums website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.