ADDRESS03: Reverse DNS entry matches name server name

Test case identifier

ADDRESS03 Reverse DNS entry matches name server name

Objective

Some anti-spam techniques use reverse DNS lookup to allow incoming traffic. In order to prevent name servers to be blocked or blacklisted, DNS administrators should publish PTR records associated with the name server addresses.

Moreover, as mentioned in paragraph 2.1 of RFC 1912 when a PTR record exists, it must match the host name.

Inputs

The domain name to be tested.

Ordered description of steps to be taken to execute the test case

  1. Obtain the IP addresses of each name server of the domain from the child using Method5. These IP addresses can be associated to the name servers through a hash table where each address is a key and the name server it's unique value. Let's call this hash table HASH1.

  2. Obtain the reverse DNS entries associated to name servers names as described in test case ADDRESS02. Let's call its outcome HASH2 which consists of IP addresses as keys and hostnames as values. As multiple PTR records are allowed, an IP address can have several corresponding hostnames.

  3. Compare HASH2 to HASH1.

    Parse the address list of HASH1.

    For an address (a) of HASH1, take the corresponding hostname (h) in HASH1. If this hostname (h) is present in the hostnames list associated to this address (a) in HASH2, then the test succeeds for address (a).

    If the hostname (h) does not match any hostnames associated to address (a) in HASH2, then the test fails for address (a).

    If the test fails for one IP address, the whole test case fails.

Outcome(s)

Multiple addresses and multiple PTR records are allowed. The test succeeds if every name server address has one or more PTR records and one of these records matches the server name. If one address doesn't match, the whole test case fails.

Special procedural requirements

None.

Intercase dependencies

Some of the input of this test comes as the result of test case ADDRESS02. ADDRESS02 must succeed prior to proceed with this test case ADDRESS03.