Please help! Pretty please? (DNS trouble, I think)

Discussion in 'Linux Networking' started by Carlos Moreno, Jan 18, 2004.

  1. Hi,

    I'm so damn frustrated by how utterly clueless I am about
    what could be the reason of this behaviour that I can't
    even begin to imagine how it is physically possible that
    it happens.

    Here's what's happening:

    I log on to the server (it's a "dedicated server" that
    we're renting from a web hoster -- it has "direct"
    connection to the net, with a static IP address), and
    type the command:

    $ telnet localhost 5555

    For about ten seconds I have no reply. Then, I get the
    expected:

    Trying 127.0.0.1...
    telnet: connect to address 127.0.0.1: Connection refused

    (there's nothing listening on that port, and there is no
    iptables rules affecting that port either)

    If I type:

    $ telnet 127.0.0.1 5555

    Then I get the expected response in zero time.


    The file /etc/hosts contains the following: (I changed
    the actual IP addresses and names, but other than that
    this is verbatim what the /etc/hosts file contains)

    --- FILE CONTENTS BEGIN ---
    # Do not remove the following line, or various programs
    # that require network functionality will fail.
    127.0.0.1 localhost.localdomain localhost
    1.2.3.4 www.domain.com
    1.2.3.5 secure.domain.com
    1.2.3.6 mail.domain.com
    --- FILE CONTENTS END ---

    The file /etc/host.conf contains a single line:

    order hosts,bind


    Can you think of something that could explain this
    behaviour?? I'm tempted to think that it's our hoster's
    DNS servers fault (I tried telnetting port 53 of their
    DNS servers, and it did take some time to reply); but
    the thing is that I can not understand or justify how
    could that affect the behaviour of a connection to
    localhost. I mean, that even if their DNS were slow,
    or misconfigured, or even completely down, I still don't
    see how that would produce a delay in establishing a
    connection to *localhost*.

    Could someone please enlighten me?

    Thanks,

    Carlos
    --
     
    Carlos Moreno, Jan 18, 2004
    #1
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  2. Carlos Moreno

    P.T. Breuer Guest

    Your resolver is broke. Your /etc/hosts is bust. "localhost"
    must resolve immediately via /etc/hosts.
    Nothing surprising, then.
    There you are - broken /etc/hosts. It's a name resolution issue.
    And hosts.allow probably doesn't allow your access from your hostname,
    nor does xinetd. Read logs and know more.
    And where is the entry for your own hostname (a FQDN)?

    Yes - broken /etc/hosts, hostname, etc. Even hosts.allow/deny
    and xinetd.conf in combo with broken hostname, domainname, etc.

    Peter
     
    P.T. Breuer, Jan 18, 2004
    #2
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  3. BTW, the problem is intermittent (has been intermittent
    for about one or two weeks). I try now, the problem shows;
    try three hours later, works fine. Try tomorrow morning,
    works fine. Tomorrow afternoon, again the problem shows,
    etc. etc.

    Carlos
    --
     
    Carlos Moreno, Jan 19, 2004
    #3
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