[geeks] simple DNS / nslookup question

[Mike Meredith]

On Sun, 02 Dec 2007 14:43:05 +0900, kevin marshall wrote:
> #nslookup yahoo.com
> 
> You will receive a response.  This does not work for all domains 
> however.  What type of record is this response (domain queries
> lacking a specific host name) and how do i set up something like this
> in bind?

A record :-

;
   IN A     148.197.254.16
   IN MX 10 betel.iso.port.ac.uk.
   IN MX 20 absinthe.iso.port.ac.uk.

That's a snippet from a real domain. Being picky, yahoo.com doesn't
lack a 'host name' as it has an associated A record. Any fqdn that
lacks an A record lacks a 'host name'.

> Of course i would get an MX record if i set type=mx and queried just
> a domain, but i'm talking about domain only queries with no specific
> type set.

Personally I prefer to use 'host' to do DNS lookups because I prefer
the syntax :-

	host any.host
		(A records)
	host -t MX any.host
		(MX records)
	host -t ANY any.host
		(Wildcard)

> FYI: Her actual problem is getting her email server (nbww.com) to
> send mail to pjgeng.org, but the DNS for pjgeng.org is screwed (no MX
> record). _______________________________________________

It's pretty unlikely but there *are* mail administrators out there who
rely on 'fallback to A-record' (and thus don't have an MX record) and
there might be MTAs configured not to behave like that. Both are bad
behaviours but we see plenty of that on the Internet :)