Host name resolution
For convenience of remembering an association with organizational
units and domains, computers are often refered by their host names.
However, applications need an IP address for remote communications over TCP/IP.
A host name needs to be resolved for its IP address.
According to the host configuration in /etc/nsswitch.conf, the
host name is looked up in "files", /etc/hosts file, then on DNS.
On private networks, where is no DNS, the host names need to be resolved
through file /etc/hosts