Re: BIND: Lookup of CNAME records

From: Lutz Petersen (akio_at_despammed.com)
Date: 03/24/04

  • Next message: Marko Cuk: "[Fwd: Linksys VPN and FreeBSD]" 
    Date: Wed, 24 Mar 2004 22:59:11 +0100
To: freebsd-net@freebsd.org

    Crist J. Clark wrote:
    > How long does it take to do a reverse-lookup on the result of the
    > previous lookups? The applications may be trying to resolve a PTR
    > record for the final IP address they end up with.

    Reverse lookups work fine. But I do not think PTR lookups are an issue
    in this case (see below).

    > You can try the following two tests and compare the difference,
    >
    > 1) Put the two external servers in resolv.conf, and run,
    >
    > # tcpdump -s512 port 53
    >
    > And try your ftp or telnet.
    >
    > 2) Put 127.0.0.1 back into resolv.conf, clear the cache of the local
    > BIND (not sure of a way to do that other than killing and
    > restarting in 8.x.x), and run the same thing,
    >
    > # tcpdump -s512 port 53
    >
    > And again try the ftp or telnet.

    I am enclosing the results of these two tests. For better readability I
    have removed the time offset and replaced my IP number with "me", the
    forwarder's IP with "fw".

    (1)
    00:00.000000 me.49235 > fw.domain: 1081+ AAAA? ftp.de.freebsd.org. (36)
    00:00.235195 fw.domain > me.49235: 1081 2/0/0 CNAME ftp4.de.freebsd.org., CNAME ftp.leo.org. (77) (DF)
    00:00.235648 me.49236 > fw.domain: 1082+ A? ftp.de.freebsd.org. (36)
    00:00.850987 fw.domain > me.49236: 1082 3/0/0 CNAME ftp4.de.freebsd.org., CNAME ftp.leo.org., A 131.159.72.23 (93) (DF)

    (2)
    00:00.000000 me.domain > fw.domain: 8207+ [1au] AAAA? ftp.de.freebsd.org. (47)
    00:00.093818 fw.domain > me.domain: 8207 2/0/0 CNAME ftp4.de.freebsd.org., CNAME ftp.leo.org. (77) (DF)
    00:00.094539 me.domain > fw.domain: 30226+ [1au] AAAA? ftp.leo.org. (40)
    00:00.183988 fw.domain > me.domain: 30226 0/0/0 (29) (DF)
    00:05.184504 me.domain > fw.domain: 52418+ [1au] AAAA? ftp.leo.org. (40)
    00:05.278765 fw.domain > me.domain: 52418 0/0/0 (29) (DF)
    00:15.278043 me.domain > fw.domain: 24089+ [1au] AAAA? ftp.leo.org. (40)
    00:15.377019 fw.domain > me.domain: 24089 0/0/0 (29) (DF)
    00:35.374320 me.domain > fw.domain: 31178+ [1au] AAAA? ftp.leo.org. (40)
    00:35.978176 fw.domain > me.domain: 31178 0/0/0 (29) (DF)
    01:15.970823 me.domain > fw.domain: 53751+ [1au] A? ftp.leo.org. (40)
    01:16.064579 fw.domain > me.domain: 53751 1/0/0 A 131.159.72.23 (45) (DF)
    01:16.065468 me.domain > fw.domain: 56474+ [1au] AAAA? J.ROOT-SERVERS.NET. (47)
    01:16.065915 me.domain > fw.domain: 36905+ [1au] AAAA? K.ROOT-SERVERS.NET. (47)
    01:16.066172 me.domain > fw.domain: 38356+ [1au] AAAA? L.ROOT-SERVERS.NET. (47)
    01:16.066372 me.domain > fw.domain: 395+ [1au] AAAA? M.ROOT-SERVERS.NET. (47)
    01:16.066572 me.domain > fw.domain: 54526+ [1au] AAAA? I.ROOT-SERVERS.NET. (47)
    01:16.066771 me.domain > fw.domain: 61085+ [1au] AAAA? E.ROOT-SERVERS.NET. (47)
    01:16.066986 me.domain > fw.domain: 38040+ [1au] AAAA? D.ROOT-SERVERS.NET. (47)
    01:16.068062 me.domain > fw.domain: 35807+ [1au] AAAA? A.ROOT-SERVERS.NET. (47)
    01:16.068664 me.domain > fw.domain: 27426+ [1au] AAAA? H.ROOT-SERVERS.NET. (47)
    01:16.069117 me.domain > fw.domain: 39377+ [1au] AAAA? C.ROOT-SERVERS.NET. (47)
    01:16.069552 me.domain > fw.domain: 11036+ [1au] AAAA? G.ROOT-SERVERS.NET. (47)
    01:16.070036 me.domain > fw.domain: 34035+ [1au] AAAA? F.ROOT-SERVERS.NET. (47)
    01:16.070476 me.domain > fw.domain: 33542+ [1au] AAAA? B.ROOT-SERVERS.NET. (47)
    01:16.157385 fw.domain > me.domain: 56474 0/0/0 (36) (DF)
    01:16.160564 fw.domain > me.domain: 36905 0/0/0 (36) (DF)
    01:16.172424 fw.domain > me.domain: 38356 0/0/0 (36) (DF)
    01:16.176809 fw.domain > me.domain: 395 0/0/0 (36) (DF)
    01:16.188828 fw.domain > me.domain: 54526 0/0/0 (36) (DF)
    01:16.193810 fw.domain > me.domain: 61085 0/0/0 (36) (DF)
    01:16.202584 fw.domain > me.domain: 38040 0/0/0 (36) (DF)
    01:16.209829 fw.domain > me.domain: 35807 0/0/0 (36) (DF)
    01:16.217073 fw.domain > me.domain: 27426 0/0/0 (36) (DF)
    01:16.238637 fw.domain > me.domain: 39377 0/0/0 (36) (DF)
    01:16.240081 fw.domain > me.domain: 11036 0/0/0 (36) (DF)
    01:16.241823 fw.domain > me.domain: 34035 0/0/0 (36) (DF)
    01:16.246842 fw.domain > me.domain: 33542 0/0/0 (36) (DF)

    As I thought of an IPv6 problem, I compiled a new kernel with IPNET6.
    That did not help at all, unfortunately.

    Any ideas?
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