[Pdns-users] Problem with Multihomed pdns server...

[Brad Knowles]

At 3:48 PM -0600 2003/04/24, Matthew Walker wrote:

>  If you specify multiple addresses in the local_address line, it binds
>  directly to them, /NOT/ to the ANY socket, so it knows where data is coming
>  from.

	Right.

>        If you don't specify any local addresses, it binds to ANY, and thus
>  doesn't know where packets are coming from.

	Right.


	My point was that (unless you specifically configure it to bind 
to explicit IP addresses) BIND solves this problem a different way, 
and simulates binding to 'ANY' by enumerating all the possible IP 
addresses and explicitly binding to each of them.  This requires that 
it periodically re-scan all the interfaces to see if any new IP 
addresses have been bound, and if any old ones have been unbound. 
This gives you the best of both worlds in this matter, but does have 
it's own consequences.

	PowerDNS does not use this technique, and you are therefore left 
either doing a real "bind to 'ANY'", or explicitly enumerating all 
the IP addresses you want it to listen on.

>  Specifying multiple local addresses has fixed it so that I only have to run
>  one instance, and it works perfectly. Thank you!

	I'm glad this has worked for you.

	There are a lot of things I like about PowerDNS (well, at least 
in theory ;-), and the ability to make the choice of binding to 'ANY' 
or explicitly enumerating all the possible IP addresses is one of 
them.  IMO, one of the biggest problems that exist with certain other 
software is that it does not give you this choice.

-- 
Brad Knowles, <brad.knowles at skynet.be>

"They that can give up essential liberty to obtain a little temporary
safety deserve neither liberty nor safety."
     -Benjamin Franklin, Historical Review of Pennsylvania.

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