The DNS name resolution process involves a DNS server checking its local cache, hosts file, and forwarding the request to higher-level DNS servers if the address is not found. As a last resort, the root hints file is used to forward the request to a root DNS server, which will then direct the request to a top-level domain server that can provide the IP address. DNS translates hostnames to IP addresses through a hierarchical system of root, top-level, and authoritative DNS servers.

1. DNS Name Resolution Process
You should be familiar with the DNS name resolution process:
1. When a DNS name resolution request is forwarded to a DNS server, the DNS
server examines its local DNS cache for the IP address.
2. If the IP address is not in the DNS server's cache, it checks its Hosts file. (Since
the Hosts file is a static text file, it is not commonly used.)
3. If the DNS server is not authoritative and configured for forwarding, the DNS
server forwards the request to a higher-level DNS server.
4. If the DNS server cannot forward the request, or if forwarding fails, the DNS
server uses its Root Hints file (also known as Cache.dns). The Root Hints file lists
the 13 root DNS servers.
5. The root DNS server responds with the address of a com, edu, net, or other DNS
server type (depending on the request).
6. The DNS server forwards the request to the high-level DNS server, which can
respond with a variety of IP addresses.
You should know the following facts about DNS:
• DNS translates a hostname to an IP address.
• The DNS hierarchy is made up of the following components:
o . (dot) domain (also called the root domain)
o Top Level Domains (TLDs) (.com, .edu, .gov)
o Domains
o Hosts
• A fully qualified domain name (FQDN) must include the name of the host and the
domain, not just the domain.
• A forward lookup uses the host name (or the FQDN) to find the IP address.
• A reverse lookup uses the IP address to find host name (or FQDN).
• A DNS server can forward a DNS request to an upstream DNS server if it cannot
resolve a host name to an IP address.
• An authoritative server is a DNS server that has a full, complete copy of all the
records for a particular domain.
• A caching-only DNS server has no zone information; it is not authoritative for
any domains.
• The Root Hints file (also called the Cache.DNS file) lists the 13 root DNS servers.
A DNS server uses the Root Hints file to forward a request to a Root DNS server
as a last resort to resolve a host name to an IP address.
• A Root DNS server refers DNS servers to .com or .edu or .gov level DNS servers.
• Recursion is the process by which a DNS server or host uses root name servers
and subsequent servers to perform name resolution. Most client computers do not
perform recursion, rather they submit a DNS request to the DNS server and wait
for a complete response. Many DNS servers will perform recursion.