TTL is an acronym for Time To Live, which is a number that represents the amount of seconds a domain name server should cache the result of a domain lookup. During the cached period the name server will serve the cached response rather than returning to the authoritative name server and re-requesting the domain information lookup.
Aux is an auxiliary value which represents a weighting of a domain name record, with lower values indicating a higher significance. Aux values are very important when used with MX records as they indicate a preference of mail server.