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I´ve been searching about this and I have found different answer for it. So I would like to explain the context. I don´t understand much about DNS records, so maybe one of you could help me. Currently. I have a domain on a website, the domain works as a mail server as well. I would like to transfer the domain to a new website, and it seems that the only thing I need to do its to create a CNAME record to points to the subdomain of the new website and other configurations that the platform of the new website told me to do (Outside of the DNS control panel) Adding the CNAME record would affect the mail service? I have a MX records pointing from my domain (example.com) to the email service example-com.mail.eo.outlook.com. And the one thing I would do is to point my current CNAME record to the new website Current CNAME record: www.example.com pointing to oldwebsite.net CNAME record after the change: www.example.com pointing to newwebsite.com

I was told specifically that I can´t bring the mail service down so. Maybe if the previous action will affect my mail server, Could you recommend me other methods to do it without having to take my mail service down?

Thank you so much!

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A CNAME CAN affect mail service but you should be OK based on the scenario you describe.

Setting up a CNAME for www.example.com should be OK (provided your email is at example.com), but a CNAME for example.com would break DNS - including breaking email delivery, and is a fairly common mistake because CNAMES do not work the way many people assume they do.

If you use an A record with the IP address instead of a CNAME this will alleviate any possible problem with email as long as your email uses MX records (which is standard).

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  • Thank you so much for the clarification. Sadly I don´t count with the IP address, just the subdomain. By the way, based on what you have told me, currently, I have a CNAME with the subdomain ftp.example.com that its pointing to example.com, Does this also cause that my email service got break? Feb 2 at 23:50
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    but a CNAME for example.com which is totally impossible per DNS specifications you can't have a CNAME record at apex, because there is already NS and SOA records there and the CNAME can no cohabit with other records. This is "emulated" by various providers with proprietary local solutions called ALIAS or APEXCNAME, etc. Today, the correct solution for this is to use DNS HTTPS(/SVCB) records. Feb 3 at 0:37
  • I don´t have that much knowledge about domains, but I have tried point the domain to another subdomain with CNAME and it worked successfully. The difference here is that this domain have a mail service, and the other one doesn´t. Even if they have the NS records, those NS are provided by the old website platform, since the new one doesn´t provide me new NS. Feb 3 at 0:46
  • having a subdomain pointing to another domain is fine in most cases - including here. It is only where the parent domain points to a CNAME that you normally need to worry, which is not the case here. You should NEVER point the whole domain to a CNAME - as @PatrickMevzek correctly says this breaks DNS.
    – davidgo
    Feb 3 at 3:38
  • @PatrickMevzek I agree with the sentiment you expressed, but I think it would be better to say that A CNAME at the APEX breaks the DNS specification (ie it is possible - in fact easy to do on most nameservers, it just does not work correctly) . I disagree that HTTPS/SVCB records are the correct solution as they are not yet an accepted standard - they are a good solution and do have excellent modern browser support, but not ubiquitous DNS server support, and they can break some APIs (AFAIK Curl does not support it, and RFC9460 is still a PROPOSED standard)
    – davidgo
    Feb 3 at 3:50

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