RFC 1912 Common DNS Errors February 1996 Don't use CNAMEs in combination with RRs which point to other names like MX, CNAME, PTR and NS. (PTR is an exception if you want to implement classless in-addr delegation.) For example, this is strongly discouraged: podunk.xx. IN MX mailhost mailhost IN CNAME mary mary IN A 126.96.36.199 [RFC 1034] in section 3.6.2 says this should not be done, and [RFC 974] explicitly states that MX records shall not point to an alias defined by a CNAME. This results in unnecessary indirection in accessing the data, and DNS resolvers and servers need to work more to get the answer. If you really want to do this, you can accomplish the same thing by using a preprocessor such as m4 on your host files.