You may receive the following error in your DNS report:
ERROR: You have one or more lame nameservers. These are nameservers that do NOT answer authoritatively for your domain. This is bad; for example, these nameservers may never get updated. The following nameservers are lame: 1.1.1.1
There are many resons for this DNS error.
[1] Nameservers are not configured properly in the DNS server.
[2] IP addresses of DNS server are not listening.
[3] Firewall configuration issue.
[4] Nameservers do not resolve proper IP addresses.
Kailash Aghera