private addresses exam question

carl_townshend · ‎05-01-2008

Hi all

on the ccent exam, if I was asked what were 2 private ips out of

10.217.1.1

172.16.1.1

127.2.2.2

225.4.4.4

which ones would be private, i would say a and b, but on one of the practice tests, it says the 127.x.x.x is private, surely this is incorrect ?

Jon Marshall · ‎05-01-2008

Carl

RFC1918 states that the private addressing ranges are

10.0.0.0 - 10.255.255.255 (10/8 prefix)

172.16.0.0 - 172.31.255.255 (172.16/12 prefix)

192.168.0.0 - 192.168.255.255 (192.168/16 prefix)

see RFC for full details

http://www.ietf.org/rfc/rfc1918.txt?number=1918

127.x.x.x is a special range of addressing designed for loopback addressing. It's not routable so in a way it could be described as a private address but if you had to choose 2 from the above it would be a & b as you say. See link for more details

http://tools.ietf.org/html/rfc3330

Good luck with your exam tomorrow.

Jon

Rick Morris · ‎05-02-2008

great answer Jon.

bs6825 · ‎05-01-2008

If you were asked a question on any Cisco exam, it is a violation of the NDA to repeat that question to anyone, including this forum.

DulleMacBath · ‎05-02-2008

Well, he said:

"Hi all on the ccent exam, if I was asked..."

Please notice the if word

"but on one of the practice tests, it says.."

Please notice the practice test words

Rick Morris · ‎05-02-2008

good catch on the "IF"

-Rick

bs6825 · ‎05-03-2008

Well said by all who saw the if and other details, original point still stands, adding an "if" may not change the facts IF the original poster added the if not to look guilty. If the person is not guilty, let my point stand as a warning to others.