OSPF wildcard mask

AlceoAlceo Member Posts: 80 ■■□□□□□□□□
Found this in Odom's book
"The answer with wildcard mask 0.255.255.0 is illegal, because it represents more than one string of binary 0s separated by binary 1s."

It means that I can't mix 0 and 1 in a wildcard mask?
All 0 must be on the left side and all 1 on the right side or viceversa with no mixed 1 & 0?

Comments

  • OfWolfAndManOfWolfAndMan Member Posts: 923 ■■■■□□□□□□
    With the wildcard, once you see at least one binary 1, the remaining that follow should be 1.

    example: to calculate a wildcard mask, say you have network 10.10.0.8 255.255.255.248. Take 255.255.255.255. Subtract your intended mask from that. Boom, you have 0.0.0.7
    :study:Reading: Lab Books, Ansible Documentation, Python Cookbook 2018 Goals: More Ansible/Python work for Automation, IPSpace Automation Course [X], Build Jenkins Framework for Network Automation []
  • DeathmageDeathmage Banned Posts: 2,496
    With the wildcard, once you see at least one binary 1, the remaining that follow should be 1.

    example: to calculate a wildcard mask, say you have network 10.10.0.8 255.255.255.248. Take 255.255.255.255. Subtract your intended mask from that. Boom, you have 0.0.0.7


    ...going to remember that for the exam! Koodos!
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