Access-lists

Discussion in 'General Cisco Certifications' started by Headache, Feb 26, 2007.

  1. laup

    laup Byte Poster

    121
    1
    24
    sorry for thread jackin.
    But does muckyfingers or any other have a special way for summarizing which network a router will advertise on its serial

    if it has

    network 172.16.16.0/24
    network 172.16.17.0/24
    network 172.16.18.0/24
    network 172.16.19.0/24

    on it ethernet ports

    answer is 16.0/22 i know but if theres a super quick way like with access lists :>
     
    Certifications: IC3,A+, N+, 70-270, CCNA
    WIP: CCDA/Job :>
  2. NetEyeBall

    NetEyeBall Kilobyte Poster

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    10
    45
    I will have to re-read over this subject but I would think you are just trying to mask out all the similar bits.

    So

    172.32.16.0
    172.32.17.0
    172.32.18.0
    172.32.19.0

    would have the following in common:

    1st and 2nd octet are the same so cound those bits = 16
    3rd octet would look like this:

    0001 0000
    0001 0001
    0001 0010
    0001 0011

    so the 1st 6 bits in the 3rd octet are similar so add that to the 16 and you got 22 bits.

    172.32.16.0 /22

    but I am going to look over some of my books again. I am really really impressed with the Cisco Academy Companion Books. Gonna have to read them cover to cover.
     
    Certifications: CCNA, A+, N+, MCSE 4.0, CCA
    WIP: CCDA, CCNP, Cisco Firewall
  3. Headache

    Headache Gigabyte Poster

    1,092
    9
    85
    Back on ACLs I came across a similar question as before. It goes something like this:

    Which wildcard mask will enable a network administrator to permit access to the internet for only hosts that are assigned an address in the range 205.25.8.0 through 205.25.15.255 ?

    I used Muckyfoot's method and came up with: 0.0.7.255

    Took me about 3 seconds.
     
    Certifications: CCNA
    WIP: CCNP

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