Name Service Woes - SGI

This is a discussion on Name Service Woes - SGI ; Hi Folks, I'm seeing some abnormality in the DNS requests that my system is sending out. This is on an Indy R5000 running 6.5.22m, full patches, without support. Firstly, some background. /etc/resolv.conf: domain domain.com nameserver xxx.xx.xxx.xxx nameserver xxx.xx.xxx.xxx /etc/nsswitch.conf: .... ...

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Thread: Name Service Woes

  1. Name Service Woes

    Hi Folks,

    I'm seeing some abnormality in the DNS requests that my system
    is sending out. This is on an Indy R5000 running 6.5.22m, full
    patches, without support.
    Firstly, some background.

    /etc/resolv.conf:
    domain domain.com
    nameserver xxx.xx.xxx.xxx
    nameserver xxx.xx.xxx.xxx

    /etc/nsswitch.conf:
    ....
    hosts: files dns
    ....

    In running `snoop -d ec0 port 53` on my system, I'm seeing that
    domain.com is being appended to the lookup I'm doing. Eg, if I
    do a lookup for "www.sgi.com", I see a query go out for
    "www.sgi.com.domain.com.".
    I've tried working with nsd via nsadmin but the problem persists.
    Switching to different nameservers residing in different domains,
    as listed in /etc/resolv.conf, does nothing, either.

    I've been sifting through the nsd posts at the archives and I'm
    also going to look through my DNS and BIND book but I wanted to
    know if anyone had any suggestions.

    Thanks,

    Josh.

  2. Re: Name Service Woes

    > I've been sifting through the nsd posts at the archives and I'm
    > also going to look through my DNS and BIND book but I wanted to
    > know if anyone had any suggestions.


    Try dropping the line:

    domain domain.com

    in /etc/resolv.conf

    There is also something in the BIND book about search orders, I think
    from memory they changed from BIND 4.8.3 to BIND 4.9 the order in which
    lookups were performed, when adding the domain name listed in
    resolv.conf.

    You might also need to explicitly set the workstation domainname as
    well.

    HTH.

    P.


  3. Re: Name Service Woes

    On Sat, 26 Feb 2005, Josh Birnbaum wrote:

    > In running `snoop -d ec0 port 53` on my system, I'm seeing that
    > domain.com is being appended to the lookup I'm doing. Eg, if I
    > do a lookup for "www.sgi.com", I see a query go out for
    > "www.sgi.com.domain.com.".


    OK, my memory on DNS and such is a bit fuzzy (I don't do a lot of
    sysadmin work), but...

    The reason this is happening is because the name resolution code
    must first assume you are trying to reach a host in your own
    domain, and thus appends the domain specified in resolv.conf.
    It will search for this host first, but if the address lookup
    fails, it will drop the appended portion and try again (and
    succeed this time).

    In other words, the name resolution code doesn't assume that
    you've specified a fully qualified host name -- it assumes
    that you've taken the shortcut of dropping the end of the
    name. That why, in your example, if you had the machine
    "foo.domain.com", and tried to look up the name "foo", it
    would give you the correct result -- it automatically appended
    the rest of the domain, just as you see happening when you
    try to look up "www.sgi.com".

    There is a way, however, to tell the name resolution code that you
    really are giving it a fully qualified host name. All you need to
    do is add a period to the end of the name (i.e. "www.sgi.com.").
    This notation signifies a fully qualified host name, and the
    name resolution code will skip any name mungeing steps and just
    look up what you gave it.

    Of course this means that if you tried to look up "foo.", it would
    fail, as there is no machine with that as its fully qualified host
    name.

    Hope that helps,
    Brent

    --
    Brent Casavant If you had nothing to fear,
    bcasavan@sgi.com how then could you be brave?
    Silicon Graphics, Inc. -- Queen Dama, Source Wars

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