Reverse DNS lookup

[Bejoy C Alias]

If a server is not having reverse entry and it is used for sending mails to external sites directly , then some of the servers to which u r sending mails will reject ur mails. This for a security purposes mainly for rejecting spam mails... . Again if the server is not having a reverse dns entry it may create some pblms for applications where there will be some access control mechanisms to prevent connections from some particular host names or ips . In this case if the server is allowed to connect only from say host1.com with ip 1.2.3.4 , the actual connections will be using ips , so the server will check the the reverse dns of 1.2.3.4 to find out whether it is from host1 or not..if it cannot do this reverse lookup , then it may create pblms... I think there wont be any pblm for web servers for reverse dns..