DNSWait

dnswait is a small script to wait for the "propagation" of a namserver configuration.

Installing

It's as easy as:

python -m pip install dnswait

There's no such thing as DNS propagation

What make your browser don't hit your server right after you've configured the zone, this long frustrating delay from hours to days, is the effect of caches, not "propagation".

Try it yourself next time you set up a new entry: just don't hit it before configuring it, so its absence is not stored in any caches. Only when configured try it and boom, cache miss all the way up, no delay, it just works.

There may be some time though between the moment you ask your registrar to set an entry (via their web user interface or their API) and the moment it's really visible on their nameservers, that time I agree to call "propagation", and that's what's being monitored by this script.

Usage

Say you've added a TXT record containing itsme to proove you're the owner of example.com, via the interface of a low-cost hosting company, and they display a nice message:

Please wait a few minutes for our scripts to propagate the change to our DNS servers.

Then you can run:

dnswait example.com TXT itsme

the script will wait for all the authoritative servers of example.com to serve itsme for your text entry, so you know exactly what those few minutes were, you don't have to guess.

Another example

Say you're the owner of mdk.fr (it's me) and your provider only allows you to change DNS records using issues on their bug tracker, then submit the issue asking them to set 51.15.187.166 as the IP for mdk.fr and run:

dnswait mdk.fr A 51.15.187.166 && notify-send "Hey they configured mdk.fr!"

so you'll know when it's done.

(If they reply "it's done" while dnswait don't see it, they probably messed up...)

Using in shell scripts

If you have a shell script updating DNS configuration via an API, you can use dnswait in them to wait for the configuration to be done.

Verbose

If you want to see what's happening, run with -v or -vv:

$ dnswait mdk.fr A 51.15.187.166 -v
INFO:dnswait:3 authoritative name servers to check.
INFO:dnswait:All authoritative servers have the expected value.

or:

$ dnswait mdk.fr A 51.15.187.166 -vv
INFO:dnswait:3 authoritative name servers to check.
DEBUG:dnswait:Checking ns-69-a.gandi.net.
DEBUG:dnswait:ns-69-a.gandi.net. have the expected value!
DEBUG:dnswait:Checking ns-173-b.gandi.net.
DEBUG:dnswait:ns-173-b.gandi.net. have the expected value!
DEBUG:dnswait:Checking ns-127-c.gandi.net.
DEBUG:dnswait:ns-127-c.gandi.net. have the expected value!
INFO:dnswait:All authoritative servers have the expected value.