> I run NAT on my firewall/router, and still host the services.
By "stuck behind NAT" I was meaning a NAT or 6-to-4 arrangement that is not under your control (so you can't configure port forwarding). This isn't all that common in the US or EU aside from mobile and satellite based providers (and you aren't likely to run servers off them!) but elsewhere it is more of an issue and will eventually become so everywhere where IPv6 take-up doesn't pick up fast enough.
> so I'm just "offline" until the link comes back up
I'm not sure what effects are common now (if any) but historically some services responded differently to the two downtime situations "DNS lookup worked, but I can't connect to that address" and "DNS lookup failed" - some MTAs used to be more likely to bounce rather than requeue for instance - so I always recommend topologically distant secondary DNS even for a single server+link situation. If you branch out later (for instance I currently have most things at home but a few bits external which I don't want down if my home link blips) you already have it setup so don't have the extras work to do. Also secondary DNS is required by the relevant RFCs, so if nothing else do it for that reason (I know you already do, I've added this bit for other readers should they stumble here in future).
By "stuck behind NAT" I was meaning a NAT or 6-to-4 arrangement that is not under your control (so you can't configure port forwarding). This isn't all that common in the US or EU aside from mobile and satellite based providers (and you aren't likely to run servers off them!) but elsewhere it is more of an issue and will eventually become so everywhere where IPv6 take-up doesn't pick up fast enough.
> so I'm just "offline" until the link comes back up
I'm not sure what effects are common now (if any) but historically some services responded differently to the two downtime situations "DNS lookup worked, but I can't connect to that address" and "DNS lookup failed" - some MTAs used to be more likely to bounce rather than requeue for instance - so I always recommend topologically distant secondary DNS even for a single server+link situation. If you branch out later (for instance I currently have most things at home but a few bits external which I don't want down if my home link blips) you already have it setup so don't have the extras work to do. Also secondary DNS is required by the relevant RFCs, so if nothing else do it for that reason (I know you already do, I've added this bit for other readers should they stumble here in future).