Caching data for shortcuts and backups in Windows 2000 Server

by Jim Boyce | Jun 18, 2007 12:00:00 AM

Tags: Jim Boyce, Windows 2000, Windows 2000 Server, servers, Windows 2000 Server Tips Newsletter

Takeaway: Caching data sets up a shortcut for accessing data down the line or whenever data might be lost. Learn how caching in Windows 2000 Server can maintain a zone file containing mappings that are essential for host and address resolution.

The primary task of Domain Name System (DNS) servers -- including Windows 2000 Servers -- is to hold a zone file and resolve host names to IP addresses for hosts in this zone. These servers are said to be authoritative for a particular domain.

DNS servers also learn about hosts and their IP addresses even if these hosts are not in their zones. For example, when a client wants to resolve a host name for a host that's not in the zone file of the local DNS server, this DNS server can call upon other DNS servers to resolve this name. After the local DNS server receives the result, it will pass it back to the client. The DNS server thus performs the query on the client's behalf and then returns the answer -- this is called a recursive query.

When the local DNS server goes out and gets the answer from some other DNS server, it will cache that information in case some other client wants to resolve the same host name. By default, all Windows 2000 DNS servers store this cache. To actually see the contents of a cache, you have to select Advanced on the View menu of the DNS console. The DNS console will then show the Cached Lookups folder with cached contents.

You can also set up a special DNS server that serves only for caching and doesn't hold any zone info. Installing a caching-only DNS server is very easy. You only have to install the DNS service on Windows 2000 Server -- you don't have to set a zone or anything else. All you have to do to use this DNS server is configure the client computers.