Re: [hybi] Alternative for SRV proposal

[Iñaki Baz Castillo <[e-mail]>]

2011/7/25 Willy Tarreau <[e-mail]>:
>> Hummm, AFAIK some local DNS resolvers automatically resolve the CNAME
>> domain to an IP before passing the DNS result to the application, so
>> the application would not be aware of the existence of a CNAME record.
>
> I'm not aware of that and it sounds strange to me.

I was not exactly right. I use a local DNS cache/resolver (called
Unbound for Linux).

- I query it a DNS A for ghs.google.com.
- Unbound queries it to the DNS server.
- It receives a reply telling that ghs.google.com has just a CNAME
record (ghs.l.google.com).
- Unbound then queries DNS A for ghs.l.google.com.
- It receives "209.85.147.121".
- Then Unbound replies to my client with two answers:
    1) ghs.google.com: CNAME, cname ghs.l.google.com
    2) ghs.l.google.com: A, addr 209.85.147.121

So yes, by inspecting the DNS response the client can realize of the
presence of a CNAME for the queried domain.




>> But this would be an extra DNS query so there would be:
>>
>> a) NAPTR + SRV +`A/AAAA
>>
>> or
>>
>> b) NAPTR + A/AAAA
>>
>> It does not fit well with constrains exposed in the other mail thread.
>
> It does fit well as something at the option of the end user, because as
> Mark says, one can send the NAPTR + A + AAAA "at zero cost" (assuming
> the uplink is infinite). It does not require extra round trips, just
> extra bandwidth and some extra synchronization from the client.

It sounds good but, wouldn't it be too much not required information?
this is, a DNS ANY query retrievesa all the resource records for the
given domain.

-- 
Iñaki Baz Castillo
<[e-mail]>