Office 365 saying DNS is managed outside, even though it's not

Hi Andy,

I understand your situation. Since you are managing your website, it is not suggested that you make any changes now.

To investigate where you host your domain:
Regarding "move to Microsoft's nameservers", I'd like to know if you let Office 365 hosts your DNS when configuring the domain setup wizard.
If so you should be required to add the following name server records in your DNS hosting register:
ns1.bdm.microsoftonline.com
ns2.bdm.microsoftonline.com
Then you will see the message "DNS managed by Office 365" and you can add the A record.
(But as the wizard mentioned, it is best that you keep the current status for your domain becase you have a website which is associated to it.)

If not, please let me know the detailed steps you did.

Meanwhile, could you provide the custom domain name for us to check it?

To protect your privacy, I have sent you a private message. You can reply to it via the steps below:
1. Go to the your details section on the right side of the community site.
2. Click Private messages 
3. Click the New Message to read and reply.

Regards,
Jim

Hi Jim,

Thank you for your detailed reply. I will send you a message now with the domain name so you can look into it further.

To confirm: when I first set up Office365 I used the domain setup wizard and I did change the nameservers to those you list which they are still configured to, plus ns3 and ns4. I haven't had to add an A record since I did this setup a couple of years ago which is why I haven't known about the issue until now.

Thanks

Andy

Hi Andy,

Sorry for the late response. I checked your domain g****.im/www.g****.im, the name server shows it should be managed by Office 365. To investigate the issue, please confirm the following information:
1. Could you also share some related screenshots for our reference? Go to Office 365 admin center, under Domains, please select the root domain and click the Domain settings and share the screenshots. You may also share the sub domain setting with us if you can find it.
Is the root domain g****.im managed by Office 365? If so can you find any custom DNS records?

2. Regarding "create a new A record for a subdomain in the DNS records and I can't", to confirm your situation, do you mean you have added the subdomain www.g****.im via the wizard, and you'd like to add another A record for it?

If so:
Normally, the sub domain www.domain.com cannot be added because the root domain is managed by Office 365. So we modify the root domain instead. Select the root domain and click Domain settings-> DNS records-> New, create an A record, type @ and point it at the website's IP and point a CNAME for www to domain.com (I checked that you have done this. It is not feasible to add the second A record for it.)

For your reference: Keep your current website when you add your domain to Office 365

Meanwhile, since Office 365 is not a DNS hosting provider, for your requirement, you may consider hosting your domain at a 3rd party hosting provider to easily add/manage more than one A records. (Note: It will cause downtime.) We appreciate your understanding.

If there's any misunderstanding, please let me know.

Best Regards,
Jim