I use dnsmasq to cache my DNS lookups. That's good. I power off my system at the end of my day, which means I lose my DNS cache. That's bad.

I pondered whether I could extract (grep/sed/awk/etc.) data from the dnsmasq logs to create a second hosts file for dnsmasq. I already use a secondary hosts file with dnsmasq to provide ad blocking (works great too!). I was thinking I could append that second hosts file from the dnsmasq logs. The file would grow very large and I don't know where the point of no return might be where performance would be impacted.

Is this idea feasible?

Second, how would I handle stale IP addresses? Possibly sort | uniq?

Thanks again.

A DNS server must maintain expiration timestamps for results, and must expire records according to TTLs. Your file based approach would have to do the same.

The loss of a DNS cache in a small environment is negligible.

Just to amplify Mr C's comments; most DNS records have an expiration period of 6 hours or less; in that context, your approach would only have a real benefit if you switched the computer back on after under 6 hours.

This feature is a real necessity in a context in which servers move.