What is a DNS cache?

A DNS cache runs locally and provides the same service as your ISP’s name servers: it resolves host names to IP addresses, and caches (temporarily stores) frequently used host names to speed up queries. There is very little configuration required for this purpose.

What is the chmod for djbdns?

Before installing djbdns, you must have daemontools and ucspi-tcp installed. The chmod is because hier.c is modifying /usr/local and /usr/local/bin to 02755 and /etc/security then complaints. Where 192.168.0.1 is the IP address where you will run the DNS cache. (with dnscache-conf)

What is the DNS configuration directory for?

This directory contains logs and configuration files that you will change later. The IP address must be configured on this computer. The IP address must not have a DNS cache or any other port-53 service. One computer can run a DNS server alongside a DNS cache as long as they are on separate IP addresses.