Stupid DNS tricks

Published October 27, 2019

The late night talk show host David Letterman used to have a segment called Stupid Pet Tricks. Well, these tricks aren't stupid but it's a fun name.

Cheaping out

You can buy a cheap nameserver on a site like NameSilo, but use something better like Route 53 for management of the actual site.

See this link.

DNS fun

DNS can be very mysterious. You don't know, did my change take effect? How long will I have to wait before it does? On a Mac, you can use networksetup -setdnsservers Wi-Fi to quickly test DNS changes. When you're done, use networksetup -setdnsservers Wi-Fi Empty to revert back.

NOTE: In my experiments, I found that setting specific name servers can completely take down your computer's ability to access the internet, albeit the hostname of the site you're trying to configure. You've been warned!

In AWS Route 53, they let you enter TXT records. What does that give you? The ability to enter free text to validate the route you think you're hitting. The host command helps with that.

host -t TXT bellagrams.org

So with this knowledge, you can test your DNS changes with something like this:

1. Create your new hosted zone entry on Route 53
2. To see changes quickly, change the TTL on your A and NS records to be something low (say 60 seconds). Do this on both Route 53 and your old nameserver provider.
3. Use networksetup -setdnsservers Wi-Fi to point to Route 53 DNS servers
• You can validate these settings by executing cat /etc/resolv.conf
4. Use host -t TXT against your hostname to validate the text doesn't show up
5. Add a TXT entry for that hosted zone with some fun text ("Hello, world!")
6. Try host -t TXT and ensure your changes have been propagated
7. Change the nameservers on your old name server host to point to AWS name servers
8. Use networksetup -setdnsservers Wi-Fi Empty to revert back

Now you have the tools needed to ensure that your DNS config understanding matches reality.