Most servers don’t ask authoritative servers for DNS directly, they usually ask a caching DNS server to do it on their behalf. These servers, through a process called recursion, sequentially query the authoritative servers at the root, main domain and sub domain levels to get eventually get the specific information requested. The most frequently requested information is then stored (or cached) to reduce the lookup overhead of subsequent queries.
If you want to advertise your Web site www.my-site.com to the rest of the world, then a regular DNS server is what you require. Setting up a caching DNS server is fairly straightforward and works whether or not your ISP provides you with a static or dynamic Internet IP address.
After you set up your caching DNS server, you must configure each of your home network PCs to use it as their DNS server. If your home PCs get their IP addresses using DHCP, then you have to configure your DHCP server to make it aware of the IP address of your new DNS server, so that the DHCP server can advertise the DNS server to its PC clients. Off-the-shelf router/firewall appliances used in most home networks usually can act as both the caching DNS and DHCP server, rendering a separate DNS server is unnecessary.
You can find the configuration steps for a Linux DHCP server in Chapter 8, "Configuring the DHCP Server".
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