regd. subnet mask - Networking

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  1. regd. subnet mask

    Can anyone please let me know :
    Why should we use an "AND"
    operator between subnet number and subnet mask?


  2. Re: regd. subnet mask

    On Fri, 01 Jun 2007, in the Usenet newsgroup comp.os.linux.networking, in
    article <1180695289.114567.83220@z28g2000prd.googlegroups.c om>,
    ramya.xyz@gmail.com wrote:

    >Can anyone please let me know :
    > Why should we use an "AND"
    >operator between subnet number and subnet mask?


    Well, you could ask your instructor - or you could grab a copy of
    the Linux Network Administrator's Guide from the LDP at
    http://tldp.org/guides.html - try either

    * The Linux Network Administrator's Guide, Second Edition
    version: 1.1
    authors: Olaf Kirch and Terry Dawson
    last update: March 2000
    ISBN: 1-56592-400-2
    available formats:
    1. HTML (read only) 2. HTML (tarred and gzipped package, 690k)
    3. PDF (1.5MB)

    or

    * The Linux Network Administrators' Guide
    version: 1.0
    author: Olaf Kirch
    last update: March 1996
    available formats:
    1. HTML (read online) 2. HTML (tarred and gzipped package, 332k)
    3. other : plain text, DVI, LaTeX source, PDF, and PostScript.
    4. various (non-English) translations

    and if it's not obvious, then use that search engine you are posting from
    to find a copy of RFC0950 and RFC1878

    0950 Internet Standard Subnetting Procedure. J.C. Mogul, J. Postel.
    August 1985. (Format: TXT=37985 bytes) (Updates RFC0792) (Also
    STD0005) (Status: STANDARD)

    1878 Variable Length Subnet Table For IPv4. T. Pummill, B. Manning.
    December 1995. (Format: TXT=19414 bytes) (Obsoletes RFC1860) (Status:
    HISTORIC)

    The key concept is the logical AND

    Address 1 192.168.0.15 1100 0000 1010 1000 0000 0000 0000 1111
    Netmask 255.255.255.0 1111 1111 1111 1111 1111 1111 0000 0000
    Address 2 192.168.2.158 1100 0000 1100 0000 0000 0010 1001 1110
    Match? yyyy yyyy yyyy yyyy yyyy yyN

    The two don't match where there is a '1' in the network mask - therefore
    they aren't on the same network.

    Old guy

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