Configure Network Services - MCSA Windows Server 2012 R2: Installation and Configuration Study Guide - page 58

You can tell that the implementation of DNS would make life a lot easier for everyone,
even those of us who like to use alphanumeric values. (For example, some of us enjoy
pinging the address in lieu of the name.) Fortunately, DNS already has the ability to handle
IPv6 addresses using an AAAA record. An A record in IPv4's addressing space is 32 bits,
and an AAAA record (4 A is in IPv6's is 128 bits.
Nowadays, most computer users are quite familiar with navigating to DNS-based
resources, such as www.microsoft.com . To resolve these “friendly” names to TCP/IP
addresses that the network stack can use, you need a method for mapping them. Originally,
ASCII flat files (often called HOSTS files, as shown in Figure 2.1) were used for this
purpose. In some cases, they are still used today in small networks, and they can be useful
in helping to troubleshoot name resolution problems.

figure 2.1 HOSTS file

As the number of machines and network devices grew, it became unwieldy for
administrators to manage all of the manual updates required to enter new mappings to a
master HOSTS file and distribute it. Clearly, a better system was needed.
As you can see from the sample HOSTS file in Figure 2.1, you can conduct a quick test
of the email server's name resolution as follows:
1.

Open the HOSTS file: C:\Windows\Systems32\drivers\etc .

2. Add the IP-address-to-hostname mapping.

3.

Try to ping the server using the hostname to verify that you can reach it using an easy-
to-remember name.