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For some time, my browser was refreshing pages very slowly, and after suggestions from other members, I added entries into /etc/modprobe.conf. After adding those entries in /etc/modprobe.conf, the browsers refresh ...
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  1. #1
    Just Joined!
    Join Date
    Apr 2005
    Posts
    1

    DNS queries with type=28 (AAAA, for IPV6)


    For some time, my browser was refreshing pages very slowly, and after suggestions
    from other members, I added entries into /etc/modprobe.conf.
    After adding those entries in /etc/modprobe.conf,
    the browsers refresh the pages very fast. The DNS queries are with type =1
    (A, IPV4 address) and the response from nameserver is seen immediately.

    However, there are some applications that still use IPV6 address in their
    queries. I have configured evolution (as a POP3 mail client) to get emails
    from gmail and here is the capture (from ethereal!)

    15 31.33984 192.168.1.102 -> 192.168.1.1 DNS C pop.gmail.com. Internet AAAA ?
    16 0.07952 192.168.1.1 -> 192.168.1.102 DNS R pop.gmail.com. Internet Addr 64.233.171.111
    17 4.92045 192.168.1.102 -> 192.168.1.1 DNS C pop.gmail.com. Internet AAAA ?
    18 0.09158 192.168.1.1 -> 192.168.1.102 DNS R pop.gmail.com. Internet Addr 64.233.171.111
    19 4.90785 192.168.1.102 -> 192.168.1.1 DNS C pop.gmail.com.hsd1.ca.comcast.net. Internet AAAA ?
    20 5.05421 192.168.1.102 -> 192.168.1.1 DNS C pop.gmail.com.hsd1.ca.comcast.net. Internet AAAA ?
    21 5.01862 192.168.1.102 -> 192.168.1.1 DNS C pop.gmail.com. Internet Addr ?
    22 0.09515 192.168.1.1 -> 192.168.1.102 DNS R pop.gmail.com. Internet Addr 64.233.171.111

    If we look at the details of one packet (15 from above), we can see the query type is 28 (for
    IPV6 address)

    DNS: ----- DNS Header -----
    DNS:
    DNS: Query ID = 31116
    DNS: Opcode: Query
    DNS: RD (Recursion Desired)
    DNS: 1 question(s)
    DNS: Domain Name: pop.gmail.com.
    DNS: Class: 1 (Internet)
    DNS: Type: 28 (IPv6 Address) <------------ IPV6
    DNS:

    Mozilla for example sends the request correctly, as seen from this

    DNS: ----- DNS Header -----
    DNS:
    DNS: Query ID = 38534
    DNS: Opcode: Query
    DNS: RD (Recursion Desired)
    DNS: 1 question(s)
    DNS: Domain Name: ads.rediff.com.
    DNS: Class: 1 (Internet)
    DNS: Type: 1 (Address)
    DNS:

    In spite of disabling IPV6 through modprobe.conf, why are some applications
    still sending DNS queries with IPV6 address ? Even if it were to send those,
    my name server seems to be responding right away and still the client
    sends the query after another 5 seconds?

    How do we circumvent this problem?

  2. #2
    Linux Newbie
    Join Date
    Mar 2005
    Posts
    230
    On the machine that is sending these AAAA queries, are you using the local BIND to resolve all domains? If so, what is your version of BIND?

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