Answer from Name server that return 127.0.0.1 for A record

vinz asked:

When resolving zapworld.com, I got the following response from the TLD server (g.gtld-servers.net.):

zapworld.com.   172800  IN  NS  ns2.developyour.net.deleted.gandi.net.
zapworld.com.   172800  IN  NS  ns1.developyour.net.deleted.gandi.net.

but ns2.developyour.net.deleted.gandi.net. points to 127.0.0.1:

;; ANSWER SECTION:
ns2.developyour.net.deleted.gandi.net.  86400   IN  A   127.0.0.1

It looks like the domain does not exist anymore, but why does ns2.developyour.net.deleted.gandi.net. to 127.0.0.1? Would it not be simpler to just return NXDOMAIN for those kind of request?

Also, what a recursive resolver is supposed to do when it faces this kind of answer? I do not find a RFC that covers this case?

My answer:


Are you writing a recursive resolver? You should not expect every possible scenario to be covered in RFCs, especially when they deal with people doing unexpected things. While they try to cover everything, this is impossible. You should do something reasonable given the circumstances.

What I expect to happen with real nameservers is that the recursive resolver will get 127.0.0.1 as the nameserver for the domain, and then send a query directly to that server (itself) with the RD bit cleared, expecting an authoritative response. The nameserver, finding it is not authoritative for the domain, ought to send a REFUSED response. I queried several public recursive resolvers for an address record in this domain. Mostly I received REFUSED responses, though a few returned SERVFAIL.

That said, this sort of behavior on the part of the DNS administrator of that domain is not very good. It puts unnecessary (albeit minimal) load on servers that do not need it. If the domain really were "deleted" then they could simply not serve any DNS records at all, or only an SOA record.


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