When you are trying to add a new PC Server or PC host it might fail with the following error message
Java.net.UnknownHostException; <Hostname or IP Address>
The reason you are getting this error message is because the communication trace is not able to reach and add the new PC host.
To fix this issue modify the "hosts.config" file located in the following path c://windows/system32/drivers/etc/ and add the host and target server
or check the DNS server with your Network administrator.
# Copyright (c) 1993-2006 Microsoft Corp.
# This is a sample HOSTS file used by Microsoft TCP/IP for Windows.
# This file contains the mappings of IP addresses to host names. Each
# entry should be kept on an individual line. The IP address should
# be placed in the first column followed by the corresponding host name.
# The IP address and the host name should be separated by at least one
# Additionally, comments (such as these) may be inserted on individual
# lines or following the machine name denoted by a ‘#’ symbol.
# For example:
# 184.108.40.206 rhino.acme.com # source server
# 220.127.116.11 x.acme.com # x client host