[Pdns-users] pdns-recursor local-address

John Miller johnmill at brandeis.edu
Thu Oct 25 14:52:44 UTC 2012

Hello everyone,

Recently, when setting up a load-balanced set of DNS servers, I ran into 
a problem where packets were being returned from a different IP address 
than they were received on.  My problem was listening on, rather 
than explicit interfaces.

In the pdns manual (Chap. 17), I see a big warning:

"Warning: When binding to wildcard addresses, UNIX semantics mean that 
answers may not be sent from the address a query was received on. It is 
highly recommended to bind to explicit addresses."

Could someone point me to some docs for these "UNIX semantics?"  For 
some perspective, we're running an Apache server (with multiple IPs), 
listening on, that returns traffic from the IP it received its 
traffic on.

John Miller
Systems Engineer
Brandeis University
johnmill at brandeis.edu

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