Thanks for opening a new thread.
The only causes I've seen for DNS failure on a SME server are either a full disk (When my SME's root partition fills up, DNS is the first service to fail) or damaged configuration.
Check to make sure you have free space on your root partition (
df -h /).
If there's any chance your dns configuration is damaged (that is, if you've been doing things to it manually), you should reset it using:
config delete dnscache
config delete dnscache.forwarder
signal-event post-upgrade ; signal-event reboot