One of the features I am working on for my app (https://bigpicture.site) is the ability for each customer to have a custom subdomain in their url (similar to slack where each workspace is in the form of {name}.slack.com.)
I understand the technical details of setting up the wildcard subdomains and handling it, but I am curious if there is a canonical list somewhere of subdomains I shouldn't let a customer register.
For instance, I wouldn't want a customer to use www as their workspace name. www.bigpicture.site should be reserved.
What other subdomain names should be reserved? Just from brain storming, here is the list I came up with. But I'd love to know if there is a better list somewhere:
www
mail
ftp
web
smtp
imap
pop
pop3
blog
support
about
social
billing
admin
knowledge
help
community
Additionally, I am going to reserve anything that starts with the letters "bp" so I can use those internally.
Otherwise you will be chasing this for a long time:
Official.example.net, postmaster.example.net, search.example.net, mail.example.net, payments.example.net
Vs
Official.users.example.net, mail.users.example.net, etc.
You may want to consider connecting with the PSL:
https://en.m.wikipedia.org/wiki/Public_Suffix_List