If C Building says "This domain's DNS is managed by another C Building account." while you set up your domain's DNS, another account started DNS hosting for it first. As long as you can manage the domain's current DNS, you can prove the domain is yours with a TXT record and take it back.
Why this happens
Any account can enter a domain in C Building and start "Let C Building manage your DNS". For that setup to take effect, though, the nameservers must be changed to C Building's at the registrar, and only someone who manages the domain can do that. Until then, the other account's setup does not affect your domain's current website or email.
For example, a colleague or a designer you worked with tried it from their own account, or someone mistyped a domain. When you then click "Read records" or "Start hosting", or "Connect to a website" on the account's Domains page, C Building says "This domain's DNS is managed by another C Building account." If the domain can be taken back, a "This is my domain, take it back" button appears below.
How to take it back
- Click "This is my domain, take it back".
- A "Take back example.com" section opens below, listing a TXT record: the type, the host
_cbuilding-reclaim, the value, and the full name_cbuilding-reclaim.example.com. - Add this TXT record at the DNS provider your domain uses now.
- Back in C Building, click "Check".
- When it works, you'll see "example.com is yours again and held for you for 3 days. Continue the setup." Then finish with Let C Building manage your DNS.
The TXT record goes in your domain's current DNS, not in C Building. What it proves is that you can manage this domain's DNS today.
If you see "The record is not on the domain's current DNS servers yet. It can take a few minutes after adding it; check again shortly.", wait a few minutes and click "Check" again.
When to delete the TXT record
Keep it until hosting has started and the nameserver steps appear. At that point C Building says: "Hosting has started: the _cbuilding-reclaim TXT record added to take the domain back can be deleted now."
After you take the domain back it is held for you for only 3 days. Once hosting starts, change the nameservers at your registrar within 3 days too, or the setup and the records brought over are removed. Read the checklist before changing nameservers first.
When a TXT record can't take it back
- The other setup is already active: the nameservers already point to C Building, managed by another account. C Building says it can't be taken back with a TXT record; contact support.
- Another account has just taken the domain back: it is held for that account for now. If the domain is yours, contact support.
- Another account is setting it up right now: C Building asks you to try again in a minute.
Unfinished setups expire on their own
If the nameservers aren't changed within 3 days of starting, the setup expires and is removed along with the records brought over. If you're not in a hurry, you can wait for the other setup to expire. Taking it back with the TXT record is faster.
If you are the account it was taken from
Your setup's status changes to "Taken back", with the message: "Another account proved it manages this domain's DNS, and the DNS setup you made for it was removed. If the domain is yours, please contact support."