Firewall rule to block DNS requests by domain ?

[dkopecek]

I'm getting flooded with DNS request for several domains that I no longer host. The domain owner has not updated the DNS servers at his registrar.
I'd like to filter any request for these domains at the firewall. If a specific rule for blocking DNS traffic exists that would be great.

Can this be done with the ASL 3.2.18 firewall ?

Something like this?:
iptables -A INPUT -m string --algo bm --string "baddomain1.com" -j DROP

[mikeshinn]

You could definitely try that, you'd want to limit it to port 53 of course.