Setting up of local resolver - Networking

This is a discussion on Setting up of local resolver - Networking ; Hi! I have a SLES9.3 server which is connected to small network without any DNS server. However the server has to be able to reolve its short name or FQDN. I configured my /etc/hosts as 192.168.0.19 bld04.my-fake-domain.com bld04 /etc/nsswitch.conf and ...

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Thread: Setting up of local resolver

  1. Setting up of local resolver

    Hi!

    I have a SLES9.3 server which is connected to small network without
    any DNS server. However the server has to be able to reolve its short
    name or FQDN. I configured my /etc/hosts as

    192.168.0.19 bld04.my-fake-domain.com bld04

    /etc/nsswitch.conf and /etc/host.conf contains

    hosts: files

    and

    order hosts

    correspondingly. So I expect my local resolver uses only local files
    instead of connectimg to remote DNS server, that is following command
    should be successfull:

    $ host `hostname`
    ;; connection timed out; no servers could be reached

    (hostname returns correct name). But it fails. I see in tcpdump log:

    bld04:~ # tcpdump -vvv -n udp -i lo
    tcpdump: listening on lo, link-type EN10MB (Ethernet),
    capture size 96 bytes
    02:53:54.968413 IP (tos 0x0, ttl 64, id 0, offset 0, flags
    [DF], length: 75) 127.0.0.1.32768 >
    127.0.0.1.53: [bad udp cksum 357e!] 34876+ A? bld04.rstl-
    private.ru.ibm.com. (47)
    02:53:59.969851 IP (tos 0x0, ttl 64, id 1, offset 0, flags
    [DF], length: 75) 127.0.0.1.32768 >
    127.0.0.1.53: [bad udp cksum 357e!] 34876+ A? bld04.rstl-
    private.ru.ibm.com. (47)

    Why it tries to connect to DNS server, moreover to local server? What
    I forgot to configure?


  2. Re: Setting up of local resolver

    Alexander Krizhanovsky wrote:
    > Hi!
    >
    > I have a SLES9.3 server which is connected to small network without
    > any DNS server. However the server has to be able to reolve its short
    > name or FQDN. I configured my /etc/hosts as
    >
    > 192.168.0.19 bld04.my-fake-domain.com bld04
    >
    > /etc/nsswitch.conf and /etc/host.conf contains
    >
    > hosts: files
    >
    > and
    >
    > order hosts
    >
    > correspondingly. So I expect my local resolver uses only local files
    > instead of connectimg to remote DNS server, that is following command
    > should be successfull:
    >
    > $ host `hostname`
    > ;; connection timed out; no servers could be reached


    Well, "host" does DNS lookups (see "man host"). The file
    "/etc/resolv.conf" will tell it which DNS server to use, otherwise it
    will use a local server by default.

    Robert
    >
    > [snip'


  3. Re: Setting up of local resolver

    On 27 , 19:22, Robert Harris
    wrote:
    > Well, "host" does DNS lookups (see "man host"). The file
    > "/etc/resolv.conf" will tell it which DNS server to use, otherwise it
    > will use a local server by default.


    Ok. I cleaned up whole /etc/resolv.conf, also I tried to remove it --
    the same result....


  4. Re: Setting up of local resolver

    Alexander Krizhanovsky wrote:
    > On 27 , 19:22, Robert Harris
    > wrote:
    >> Well, "host" does DNS lookups (see "man host"). The file
    >> "/etc/resolv.conf" will tell it which DNS server to use, otherwise it
    >> will use a local server by default.

    >
    > Ok. I cleaned up whole /etc/resolv.conf, also I tried to remove it --
    > the same result....
    >


    You need to specify what your problem is.

  5. Re: Setting up of local resolver

    Thank you for the replies!

    On 30 , 14:19, Robert Harris
    wrote:
    > You need to specify what your problem is.


    Well. Try to explain better.

    When I run host `hostname` I see in tcpdump DNS requests to local
    machine (requests on loopback interface), but comman returns with
    error meassage. I configured /etc/hosts, /etc/nsswitch.conf, /etc/
    resolv.conf and /etc/host.conf (see first message), but my local
    resolver (resolver on local files) still doesn't work.

    I need to configure resolver for work with local files only because I
    haven't real DNS server in my network.


  6. Re: Setting up of local resolver

    On Mon, 30 Jul 2007 05:29:12 -0700, Alexander Krizhanovsky
    wrote:

    > When I run host `hostname` I see in tcpdump DNS requests to local
    > machine (requests on loopback interface), but comman returns with
    > error meassage.


    That would be because "host" _always_ uses DNS. It does not ever use
    /etc/hosts and there is no way to make it do so. It is after all a tool
    for testing DNS. If you must have it working then you need to set up a
    local DNS or point /etc/resolv.conf to a working DNS.

    If you just want to see if your setup is right, try another program like
    "ping". It should use local files first.


    --
    -| Bob Hauck
    -| "Reality has a well-known liberal bias." -- Stephen Colbert
    -| http://www.haucks.org/

  7. Re: Setting up of local resolver

    On 30 , 17:44, Bob Hauck wrote:
    > That would be because "host" _always_ uses DNS. It does not ever use
    > /etc/hosts and there is no way to make it do so. It is after all a tool
    > for testing DNS. If you must have it working then you need to set up a
    > local DNS or point /etc/resolv.conf to a working DNS.
    >
    > If you just want to see if your setup is right, try another program like
    > "ping". It should use local files first.


    Thank you very much for the kindly answer!


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