I have web app that I want to test for DNS failures because I think it don't handle them correctly, how can temporarly make all DNS lookup return error?I'm using Xubuntu (XFCE).
How to emulate dns failure in web browser?
dns;xfce
@schaiba suggested renaming /etc/resolv.conf; a little better would be to make /etc/resolv.conf point to a live address without a DNS server running.  That is likely to reduce the timeouts.