Graham Seaman wrote: > >>What (if anything) writes to /etc/resolv.dnsmasq? > > Nothing at all. This is a static file created by hand for dnsmasq and > nothing else knows about it. > > It hasn't failed again since I wrote originally; if it does I'll check > the time on the file before I do anything to it just in case something > has written to it - but I don't see how it could. >
It's worth looking the the syslog: dnsmasq logs each time it reads the file, and the set of servers it's using as a result, so you can see if that looks as expected. My guess is that one of the two upstream servers was borked, and returning empty answers: re-loading the resolv file had the effect of swapping to the other (working) server and fixed things. This is hard to diagnose, because dnsmasq will change the server it's using at seemingly random points. If it happens again try queries (with dig, or nslookup) direct to the upstream servers. Later dnsmasq releases have subtle improvements in the code to detect and ignore broken upstream servers, but in the end this can always be a problem: if a server lies and says "no such domain" dnsmasq has, in the end to believe it. HTH Simon.
