[dheera]

Is there a way to tell your system to fall back to the last known IP address if DNS server isn't reachable?

Basically soft-invalidate your local DNS cache but it back from the cache graveyard if DNS is down.

[elithrar]

You could run a local resolver like dnsmasq or Unbound that can “serve stale” on upstream failures, but that assumes the DNS failure is a client-facing resolver one.

From what I observed here, it was more internal DNS related: Newegg was serving an opaque “DNS failure” error page from Akamai’s front-end which is likely because their infra was failing to resolve names internally.

[TimWolla]

Unbound has a 'serve-expired' option: https://nlnetlabs.nl/documentation/unbound/unbound.conf/#ser...

[bombcar]

It should be possible to set your cache so it lives forever but still checks for a new IP at normal expiring time.