I have 2 DNS Severs : ns1.host.com = HostIP1 ns2.host.com = HostIP2 when i do reverse lookup i get: ns1.host.com -> HostIP1 ns2.host.com -> HostIP2 So far so good ! Now i add clients and point the client to host name server, add A records and all everything works fine. When i do a reverse check on client.com using mxtoolbox i get error: Invalid SuperTool Syntax Invalid Input. ptr requires a IP Address and client.com is a Fully Qualified Domain Name. Should ptr records be created for all clients as well ?