Re: Pick a name, any name...
"John H. Robinson, IV" <jhriv@ucsd.edu> writes:
> because with a A record one lookup -> IP address(es)
> with a CNAME one lookup -> another lookup -> IP address(es)
>
> CNAME cause you to at least DOUBLE the DNS lookups, DOUBLING the
> potential timeouts, DOUBLING dns load
>
> can you do it? certainly. should you be aware of the effects WHEN you do
> it? yes. you may break the rules only after you understand the rules.
There is no rule that CNAME records are only for non-local pointers.
Yes, a CNAME does additional lookups. DNS traffic to leaf servers
is an insignificant piece of total traffic.
> > DNS entries are cached and don't cause that much traffic.
>
> the second and subsequent times, yes. not the first time.
A local CNAME doesn't do double traffic. Suppose I have a CNAME for
www.bar.baz -> fletch.bar.baz.
Looking up an A record in this domain will require:
query for baz.
query for bar.baz.
query for fletch.bar.baz.
Looking up the CNAME is only 33% more traffic, not "at least double":
query for baz.
query for bar.baz.
query for www.bar.baz.
query for fletch.bar.baz.
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