/etc/resolv.conf is actually a symlink to /tmp/resolv.conf which regularily gets rewritten by the dnsmasq init script, possibly during a reload event.
To temporarely use a persistent resolv.conf, first delete the symlink, then recreate it as plain file:
rm /etc/resolv.conf
echo "nameserver 8.8.8.8" > /etc/resolv.conf
I am not sure about your DNS resolution problems with dnsmasq, its the first report of this kind I heard of so at least it is not a widespread common issue with snapshots.
Maybe take a look at logread to see if there's obvious problems.