Stop using ISP DNS
Stop using ISP DNS.
It's that simple.
Just plug several dozen public DNS (google, opendns, etc.) into your computer, or your router, or your servers as upstream DNS's and forget about it. When one doesn't resolve, it'll bounce down to the next and you won't even notice.
Honestly, the days of being dependent on your ISP DNS are over. The only problems now are if the ISP intercepts all DNS (then you deploy DNSSEC to talk to the root servers directly).
But everybody, whether they own just the client, just the ADSL router, or a bank of servers, can just plug in dozens of other DNS's as they see fit and it will not hurt performance in any way. Order them properly and it'll even take your preference into account for you.
Hell, my first DNS is my own VPS - which has my host's DNS, Google, then the roots. My 2nd and 3rd are Google. The rest are random public freebies like OpenDNS. And at the bottom of the list are the ISP DNS. I plug these settings into my ADSL router which hands them out via DHCP, and also hands itself out as the primary (which also just has the list above in it) so all my client devices get them.
Whenever someone cries that Virgin DNS or whatever is down, I've never ever noticed a problem unless there is literally no connectivity to the net at all (at which point, I switch on 3G and carry on, because access to the DNS isn't dependant on using my ISP connection).