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: 184.108.40.206
There are many resons for this DNS error.
 Nameservers are not configured properly in the DNS server.
 IP addresses of DNS server are not listening.
 Firewall configuration issue.
 Nameservers do not resolve proper IP addresses.