Advertisement
If you have a new account but are having problems posting or verifying your account, please email us on hello@boards.ie for help. Thanks :)
Hello all! Please ensure that you are posting a new thread or question in the appropriate forum. The Feedback forum is overwhelmed with questions that are having to be moved elsewhere. If you need help to verify your account contact hello@boards.ie

CCNA (tech?) Q: Class C IP Address

Options
  • 20-01-2011 11:46pm
    #1
    jc77
    Registered Users Posts: 548 ✭✭✭


    Hi, started the CCNA self-taught yesterday. Quick question regarding Class C address...

    Details of PC I worked on;
    IP: 192.168.1.xx
    S/M: 255.255.0.0
    G/W: 192.168.x.x

    My notes tell me that Class C addresses have a subnet mask of 255.255.255.0 & Class B 255.255.0.0. The IP address begins with 192 indicating Class C, yet the S/M indicates Class B.

    Is the S/M set by the user/admin or class?
    If set by class, how is the above possible?

    Thanks


Comments

  • Options
    #2
    _CreeD_
    Registered Users Posts: 4,147 ✭✭✭_CreeD_


    Remember class is not a limitation anymore. Engineers sometimes still use it when describing network ranges but that's just out of habit. Unless the software you're trying to run with (Router, dynamic routing protocol, end client stack etc) has severe classful limitations there is no rule that says a 192.168.x.x network has to have a /24 mask. CIDR is king.

    More directly the mask is administrative, think of it as nothing more than you teaching the device it's layer 2 boundaries with binary math.


Advertisement