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.
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