local lookups ok, remote lookups broken.

Kevin Darcy kcd at daimlerchrysler.com
Tue Dec 23 00:21:16 UTC 2003


i18rabbit wrote:

>i am confused as to who is at fault
>for reverse DNS lookup failures.
>i would sincerely value any help.
>
>network:
>
>A                  B                 C            D
>MyLocalGateway <-> MyISPsNetwork <-> Internet <-> RemoteServer
>
>all lookups for A when using A's DNS work fine.
>all lookups for A when using B's DNS work fine.
>reverse lookups for A when at D fail when not
> specifying any particular DNS server to use
> in a host(1) command (this problem causes my email
> from A to be rejected by mail servers that do
> reverse DNS lookups - BAD problem).
>reverse lookups for A when at D work fine only when
> specifying B's DNS servers in a host(1) command.
>
>there is no problem locating A in any browser/ftp/etc,
>from any location, whether numeric or "human-readable"
>forms are used when specifying A's location.
>
I don't understand this paragraph. What do you mean by "locating" and/or 
"A's location" in this context? You already said above that remote 
servers can't do a reverse lookup of A. Are you trying to say here that 
forward lookups work, but reverse lookups do not?

>who's fault is it that reverse dns lookups for A
>do not work from remote servers on the Internet?
>
Does "B" happen to be a slave for the relevant reverse zone? That's an 
important piece of information. If so, then basically your problem boils 
down to "names in the reverse zone resolve only when the queries are 
explicitly sent to an authoritative nameserver". This is symptomatic of 
a delegation problem of some sort. If you would name the actual zone in 
question, one could investigate further...

                                                                         
                                                            - Kevin




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