Assume we have a plain Unbound DNS server with one IP address for clients. Now we want to assign a second IP address. We changed a configuration file and restarted our Unbound.
Testing
We are querying the first IP address using dig and everything works fine but when we are querying the second address we are getting the following answer.
... ;; reply from unexpected source: x.x.x.x#53, expected y.y.y.y#53 ...
How to fix it?
The problem occurs because Unbound uses addresses x.x.x.x and y.y.y.y for receiving queries but the only x.x.x.x for sending answers. How to fix it? Use the following option in configuration file.
interface-automatic: yes
This tells the server to use x.x.x.x address to replying to the queries directed to x.x.x.x and y.y.y.y to replying to the queries received by y.y.y.y address.