creating a wildcard subdomain in google domains - google-domains

Question

I want to create a wildcard subdomain on my google domain so that every subdomain points to the main site.
So for example if my website is called abc.com any subdomain hello.abc.com/ xyz.abc.com/etc.abc.com to all point to the main site.
Is there a way to do this in google domains?

Answer 1

I managed to do it like that:
for the exact match example.com I use: # in Name.
for all wildcard matches *.example.com I use: * in Name.
so I have:
Name
Typ
TTL
Data
#
A
1h
123.123.123.123
*
A
1h
123.123.123.123

Answer 2

Use the wildcard character * as in *.example.com.
About wildcard records

Answer 3

I solved this recently and I got annoyed at how long it took me to find an answer. I'm going to go through this here really quick, because this is the SO question I landed on when I searched for the problem and the answers didn't help. If I ever come back here again, I'd prefer to have it answered. Maybe it'll help someone else too.
A Stupidly Simplistic Description of DNS
When your computer wants to talk to another computer, it has to figure out where it is. Computers use numbers instead of nice names, so smart people invented DNS to do that translation. For our purpouses, a DNS server is just a thing that stores a bunch of information about how to translate nice human names like google.com into annoying computer names like 19:3f:93:27:40...
To do this it stores a bunch of records. these are just rows in a database somewhere.
A Too-Short Summary Of The Record Types Involved.
DNS has two types of records relevant to this problem:
A Records
Address records directly map from a human name to a computer name.
Here's what it looks like (roughly) circa 2023 in google domains. If you're like me and too cheap for a static IP, this will be in dynamic dns, otherwise it'll be somehwere else.
CNAME Records
CNAME records point to other records, specifically A records. If you want traffic for some subdomain to go to a specific place, you create a CNAME record. That way when someone asks the DNS system for "wiggling.worms.com", it will actually give them the IP for "worms.com", or wherever your computer/network is actually located. The record looks like this:
whenever anyone asks the DNS system "where is somesubdomian.yourdomain.com?", it will answer with whatever the result of looking up "yourdomain.com" is. More about debugging this in a bit.We're almost there.
First, I want to spend a sentence or two venting, skip to the next paragraph if you don't want to hear it. Many answers on many sites I've seen said that the "yourdomain.com." part of this was arbitrary, and could be "anything.yourdomain.com.". This is incorrect. When the DNS system encounters a CNAME record, it will follow it as written, which means if you use "anything.yourdomain.com", and you don't happen to have an A type record for "anything.yourdomain.com", the DNS query for "somedomain.yourdomain.com" will fail. This is probably very obvious to people who are not hastily slapping together a homelab, but it was very frustrating finding so many easily accessible answers that were simply wrong.
OK. Last bit.You pay good money for that domain and everything under it! Wouldn't it be nice to not have to make a CNAME record for every subdomain you could possibly use? Well now you can, with wildcard CNAME records! In the hostname part of the CNAME record, simply put "*" when you're bored of creating endless records and ALL subdomains matching that pattern will be routed to the associated record. NEAT.
Debugging - Because Things Go Wrong
You thought you did it right, why doesn't it work? Fortunately, people thought of this, and made tools. I used dig, because I learned it in school. You can also use other tools as are available on your system, notably nslookup for windows. These tools let you look at what's actually going on when you talk to the DNS system. For example:
pi#raspberrypi:/ $ dig google.com
; <<>> DiG 9.11.5-P4-5.1+deb10u5-Raspbian <<>> google.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 35586
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;google.com. IN A
;; ANSWER SECTION:
google.com. 178 IN A 142.250.188.14
;; Query time: 12 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Thu Feb 16 19:00:23 GMT 2023
;; MSG SIZE rcvd: 55
We figured out where google is, but how did we get there? dig has a (weirdly formatted) +trace option that will tell us about the whole path we took to get the answer:
; <<>> DiG 9.11.5-P4-5.1+deb10u5-Raspbian <<>> google.com +trace
;; global options: +cmd
. 26362 IN NS a.root-servers.net.
. 26362 IN NS b.root-servers.net.
. 26362 IN NS c.root-servers.net.
. 26362 IN NS d.root-servers.net.
. 26362 IN NS e.root-servers.net.
. 26362 IN NS f.root-servers.net.
. 26362 IN NS g.root-servers.net.
. 26362 IN NS h.root-servers.net.
. 26362 IN NS i.root-servers.net.
. 26362 IN NS j.root-servers.net.
. 26362 IN NS k.root-servers.net.
. 26362 IN NS l.root-servers.net.
. 26362 IN NS m.root-servers.net.
;; Received 525 bytes from 127.0.0.1#53(127.0.0.1) in 0 ms
com. 172800 IN NS a.gtld-servers.net.
com. 172800 IN NS b.gtld-servers.net.
com. 172800 IN NS c.gtld-servers.net.
com. 172800 IN NS d.gtld-servers.net.
com. 172800 IN NS e.gtld-servers.net.
com. 172800 IN NS f.gtld-servers.net.
com. 172800 IN NS g.gtld-servers.net.
com. 172800 IN NS h.gtld-servers.net.
com. 172800 IN NS i.gtld-servers.net.
com. 172800 IN NS j.gtld-servers.net.
com. 172800 IN NS k.gtld-servers.net.
com. 172800 IN NS l.gtld-servers.net.
com. 172800 IN NS m.gtld-servers.net.
;; Received 1170 bytes from 199.7.91.13#53(d.root-servers.net) in 12 ms
google.com. 172800 IN NS ns2.google.com.
google.com. 172800 IN NS ns1.google.com.
google.com. 172800 IN NS ns3.google.com.
google.com. 172800 IN NS ns4.google.com.
;; Received 836 bytes from 192.43.172.30#53(i.gtld-servers.net) in 12 ms
google.com. 300 IN A 142.251.214.142
;; Received 55 bytes from 216.239.38.10#53(ns4.google.com) in 50 m
If you set this up wrong, running this should give you an idea of what exactly you're doing wrong. For me it showed that there was no record for "any.mydomain.com" and so the dns resolution for "somethingelse.mydomain.com" was failing. There are other issues you might run into, but for this question, that's probably the big one.
OK. I think that mostly covers it. It's probably overkill, but if it's helpful to one person it's worth it. Including me in the future.