wget not resolving domain names

[Paul Howarth]

Derek Martin wrote:
> On Thu, Nov 03, 2005 at 10:39:00AM +0000, Paul Howarth wrote:
> 
>>>Well, what is supposed to happen is that the MTA first looks up the MX
>>>record for the host that you specified, and THAT is used -- ater that,
>>>if no MX record exists, it should do an A lookup and convert CNAMEs.
>>
>>That's debatable because there should not be any MX records for a name
>>that has a CNAME record - see for example RFC 1912, section 2.4 "CNAME
>>records":
> 
> 
> It isn't debatable; until the MTA does the lookups, it doesn't know
> that the address is a CNAME or an MX or what it is.  The MTA should
> and does (at least with sendmail) look for MX records for the supplied
> name first.  Only if none are found does it do an A record lookup,
> which is when it would discover the CNAME record.

Actually it gets the CNAME back when it does the MX lookup, so there's 
no need to do the follow-up lookup of the A record:

$ dig www.uit.no mx

; <<>> DiG 9.3.1 <<>> www.uit.no mx
; (1 server found)
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 11161
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 1, ADDITIONAL: 0

;; QUESTION SECTION:
;www.uit.no.                    IN      MX

;; ANSWER SECTION:
www.uit.no.             86400   IN      CNAME   w3s2.uit.no.

;; AUTHORITY SECTION:
uit.no.                 43200   IN      SOA     benoni.uit.no. 
hostmaster.uit.no. 2005110300 14400 1800 1209600 43200

>>>But this is just another example of a good reason not to
>>>use CNAMEs.  I never use them... they only create problems.
>>
>>They're useful as long as you know what you're doing :-)
>>Too bad too many people don't :-(
> 
> 
> I don't really agree; they're totally redundant.  You're better off
> just using an A record.  That will always behave intuitively and
> completely avoids all the stupid problems associated with CNAMEs.

True; it's a shame CNAMEs can't be "uninvented" really.

Paul.