[question] new bind option "max-recursion-depth"

[Evan Hunt]

On Wed, Dec 17, 2014 at 05:20:09PM -0500, Barry Margolin wrote:
> But each CNAME is in a different domain, and their nameservers were in 
> yet other domains. So while resolving the CNAME chain, you also have to 
> perform several levels of recursion.
>
> Does the max-recursion-depth limit apply to all of these combined, or 
> does each step in the chain start at zero?

It limits how deep the server will go at any one time.  If looking up a
name server requires looking up a second name server which requires looking
up a third, they're each pushed on to a stack.  Eventually (one hopes), you
reach bottom and pop back up.  If it turns out the name you asked for is
a CNAME, then you start a new stack while you resolve the CNAME target.
As long as the stack never exceeds seven layers of recursion, you're
fine.

-- 
Evan Hunt -- each at isc.org
Internet Systems Consortium, Inc.