03-02-2009 06:59 PM - edited 03-06-2019 04:20 AM
Hi every body!
Let say we have class C 192.192.192.0 network with subnet mask 255.255.255.192
The total number of subnets are:
192.192.192.0
192.192.192.64
192.192.192.128
192.192.192.192
According to cisco book , the valid subnnets are = total subnets-2
The subnet "192.192.192.0 " and " 192.192.192.192" are not considered valid subnets . My question is why?
Thanks a lot!
Solved! Go to Solution.
03-02-2009 07:28 PM
Sarah,
Here's a paper that explains why usage of the subnet zero and all one's subnet was discouraged by RFC950.
Subnet zero and all one's are now widely used.
http://www.cisco.com/en/US/tech/tk648/tk361/technologies_tech_note09186a0080093f18.shtml
Regards
03-02-2009 08:04 PM
Sarah
To be bit less subtle that Harold, the book you reference is presenting a very old (and out moded) view of the principles of subnetting. In modern practice neither of the subnets is not permitted. (you might however, be careful on certification tests, some of which may still reflect the old practice).
HTH
Rick
03-02-2009 07:24 PM
IP Addresses 192.192.192.0 & 192.192.192.192 are not valid IP ADDRESSES because they are subnet addresses.
I think this is one of those trick questions again.
03-02-2009 07:28 PM
Sarah,
Here's a paper that explains why usage of the subnet zero and all one's subnet was discouraged by RFC950.
Subnet zero and all one's are now widely used.
http://www.cisco.com/en/US/tech/tk648/tk361/technologies_tech_note09186a0080093f18.shtml
Regards
03-02-2009 08:04 PM
Sarah
To be bit less subtle that Harold, the book you reference is presenting a very old (and out moded) view of the principles of subnetting. In modern practice neither of the subnets is not permitted. (you might however, be careful on certification tests, some of which may still reflect the old practice).
HTH
Rick
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