Zone Files and Resource Records

Summary

This chapter described the format and content of zone files. You learned about the $TTL directive, used to set the default TTL for the zone. You also encountered the $ORIGIN directive, used to set the base name for the zone, and the $ORIGIN substitution rule, the cause of much DNS aggravation. Using the example zone file as a guide, the text explained the various Resource Record types used to construct basic zone files such as the Start of Authority, Name Server, Mail Exchanger, and Address Resource Records.

Chapter 3 explains DNS operations: the types of DNS queries that may be used; reverse mapping, the process by which an IP address may be mapped to a host name; zone transfers, the method by which zone files are updated from the master to the slave name servers; and finally, a brief overview of the security issues involved in running a DNS service.