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 CNAME records not replicating

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Rene's profile image
Rene posted Sun August 31, 2025 01:56 PM

Hi,

I have created 5 CNAME records for subdomains to a domain I own and have configured.
All five records are straightforward links to sites published on Netlify, and all have default settings for TTL.

It has been more than 24 hours, and so far, only 2 of the 5 subdomains work.  The other three generate DNS errors.
I have checked and double-checked for any typos, but am unable to find any.
Also, the names are unique.

What could be other reasons these three CNAME records are not replicating?
There is no error message in NS1, so I am assuming I am not hitting some arbitrary limit on the number of records or something like that.

Any suggestions would be much appreciated.

Duong Bui Thi Thuy's profile image
Duong Bui Thi Thuy

Hi Rene,

Can you please let us know the CNAME records which does not work? We can check them and provide you with some advice.

Thanks

Valentina Collier's profile image
Valentina Collier

Hi Rene, CNAME propagation delays or partial replication can happen for a few reasons. First, verify that the non-working records aren’t conflicting with existing A or TXT records for the same subdomains, as that can block proper resolution. Next, confirm that Netlify’s target hostnames are correctly formatted and active — sometimes a misconfigured target endpoint can cause DNS lookup errors. Also, clear your DNS cache or test using external tools like dig, nslookup, or dnschecker.org to see if the issue is global or local. If replication remains inconsistent after 48 hours, it’s worth opening a support ticket with IBM NS1, as there could be a zone synchronization issue on their end.