All Subdomain Stopped working

Hi All

I hope someone can help me with this one.

I've searched around the internet and the forum. So far I cannot find a scenario such as mine or a solution to my problem.
A few days ago I noticed that subdomains for all domains hosted on my server are no longer accessible. I have not done any changes. There was a CWP update a few days ago but seeing as no one else is complaining that might not be the cause.
The fact that they were working before, means the A record was added when the domain was created. There is no cloudflare in use for any of the domains.

BIND stops and starts with no issues. I cannot ping any of the domains. I creating a new domain but the same issue.

I then went to my domain register and added an A record for one of the domain hosted on my server. That subdomain is accessible. Hoping this helps pinpoint the problem.

Thank you

Kindly provide your nameservers.  Did you recently renew or transfer the domain the ns are on?

ns1.activetech.co.za
ns2.activetech.co.za

No. This is the main domain that I've had for a few months.

looking up yoru glue records, there is a problem
IPv4 Glue records for ns1.activetech.co.za
ns0.is.co.za.   86400   IN   A   196.4.160.17

You need to log into your registart and add glue/host records for ns1 and ns2 to point to your servers ip

Very interesting.
So I had the nameserver addresses set to 127.0.0.1. When I ping the nameserver the response came from my local machine. Lol. For some odd reason, this config worked before.

So : I Updated the IP addresses of the name servers, waited a few hours for propagation. Now everything is working fine again.

Thank you for answering my questions and solving my problems 100% of the time.