DNS Error

Re: DNS Error

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> Reply to: Re: DNS Error
>I would be interested in your detailed explanation regarding what to have US
>West do - I don't have any errors but I recently switched over to US West
>and I
>am on my 3rd set of static IP's due to some problem they are having. I
>beleive
>my DNS server is configured correctly but I want to make sure US West is
>doing
>what they are suppose to. I want to be very specific with them as I don't
>want
>duplicate info on there DNS.

This is a FAQ. Evidently, many people find this subject initially confusing.

THEORY:
When a resolver tries to look up the pointer record for an IP address, it
starts at the top, the root-servers. In the case of Mr. Stempnakowski,
whose addresses are around 207.225.27.225, the root servers delegate the
surrounding class B subnet (207.225.x.x) to a couple of US West servers.

The US West servers in question then further delegate the specific class C
subnet (207.225.27.x) to a different pair of US West servers.

At this point, the resolver asks one of these servers for a PTR record. It
*should* respond with one of two answers: either a final answer, or a
further ("classless") delegation. If it gives a final answer, then the
resolver will never ask Mr. Stempnakowski's servers, since they're not
authoritative.

In the case of a classless delegation, it should point to Mr.
Stempnakowski's name servers, which should then have the PTR record in
question.

REALITY:
<ns1.uswest.net> instead responds with an SOA record for the
<27.225.207.in-addr.arpa.> zone. This means that, while it is authoritative
for the zone, it doesn't have the answer we're looking for. In other words,
the answer doesn't exist. Even if <dns1.ski-haven.com> has the correct
answer, it'll never get queried.

SOLUTION:
US West has two possible courses of action available, and doing nothing is
neither of them. Unfortunately, doing nothing seems to be the preferred
solution of a number of network providers.

1) Delegate the classless subnet that Mr. Stempnakowski is using. This is a
complicated process, but is better in the end. If you have subscribed to
the list for a while, you've probably seen my repeated reposts of Sigfus
Magnusson's excellent description of how this works since he first posted
it last June.

QuickDNS Pro Admin's Domain Assistant has a selection for creating
classless reverse zone files, but I just tried it and couldn't get it to
work.

2) Add PTR records for the addresses in question to their
<27.225.207.in-addr.arpa.> zone file. Preferably, these should resolve to
names that in turn resolve back to the addresses, such as
<dns1.ski-haven.com.>, etc. This should only take them a moment, so they
really have no excuse not to do so.
________________________________
Chris Buxton
Internet and Database Consultant

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