"What's the use of their having names," the Gnat said, "if they won't answer to them?"
The latest BIND nameservers, versions 8.4.7 and 9.3.2, have lots of new features. Some of the most prominent introductions are support for dynamic updates, asynchronous zone change notification (called "NOTIFY" for short), and incremental zone transfer. Of the rest, the most important are related to security: they let you tell your nameserver whom to answer queries from, whom to serve zone transfers to, and whom to permit dynamic updates from. Many of the security features aren't necessary inside a corporate network, but the other mechanisms will help out administrators of any nameservers.
In this chapter, we'll cover these features and suggest how they might come in handy in your DNS infrastructure. (We do save some of the hardcore firewall material 'til the next chapter, though.)
Before we introduce the new features, however, we'd better cover address match lists. BIND 8 and 9 use address match lists for nearly every security feature and for some features that aren't security-related at all.
An address match list is a list (what else?) of terms that specifies one or more IP addresses. The elements in the list can be individual IP addresses, IP prefixes, or a named address match list (more on those shortly).[*] An IP prefix has the format:
network in dotted-octet format/
bits in netmask
For example, the network 22.214.171.124 with the network ...