The Address (A) record associates a domain name with an IP address, which is the primary purpose of the DNS system. The Pointer (PTR) record provides data for reverse DNS, which is used for logging the domain name and verification purposes.Also called inverse DNS, the PTR record is an option. See reverse DNS.he Address (A) record associates a domain name with an IP address, which is the primary purpose of the DNS system. The Pointer (PTR) record provides data for reverse DNS, which is used for logging the domain name and verification purposes.