Comment by vbezhenar

My two most common problems:

1. Need to change IP as soon as possible, but DNS record has huge TTL (e.g. 24h).

2. Client ISP DNS does not resolve my domain and it's absolutely not clear how to proceed from here. I don't have connections in huge ISPs, writing stuff to ISP support is as effective as throwing stones in the lake.

Funnily enough, for both cases, /etc/hosts or its Windows equivalent comes to the rescue.