Only one name server detected

What this means

It is recommended to have at least 2 name servers for redundancy and reliability.

A single name server creates a single point of failure.

If this name server fails or becomes unavailable then DNS lookups for your domain will fail which can have wide ranging impacts on services.

Use the dig command to list the NS records and count the number of name servers.

dig ns example.gov.uk +short 

ns1.example.gov.uk 

ns2.example.gov.uk

If the amount of name servers return is less than 2 then you should plan to increase the number to 2 or more.

Check the IP address of the servers to make sure they are different.

If they are the same then this could imply that a single server is responsible for serving requests to both servers.

Provision additional name servers if there are fewer than 2.