Many A-records

Jonathan de Boyne Pollard J.deBoynePollard at Tesco.NET
Sat Apr 10 18:47:47 UTC 2004


JL> Every time you create a CNAME where you could have used an A
JL> record you create a situation where every resolver looking
JL> for your service must do two lookups instead of one.

BM> Unless the server is authoritative for both the CNAME record
BM> and its target.  In that case the server will return both
BM> records, [...]

JdeBP> If the first client-side aliase leads out of the server's
JdeBP> bailiwick, then the resolving proxy DNS server _still_ needs 
JdeBP> to perform further lookups, because the second alias in the
JdeBP> chain will be discarded as poison.

BM> Yes.  That's not what I was talking about 

Yes, it is.

BM> I specifically said "if the server is authoritative for both 
BM> the CNAME record and its target."  

And that's exactly the case with the example that I gave.  Look at the content
DNS servers that I mentioned, and what they publish, again.  The one set of
content DNS servers is authoritative for the _entire_ alias chain.  However,
the chain crosses bailiwicks, necessitating multiple lookups.

BM> This isn't an uncommon configuration [...]

I know.  I pointed at a public example of it, after all.


More information about the bind-users mailing list