Changing the HOSTS file

When you install IBM Spectrum® Control on your Windows™ operating systems, you must follow these steps to avoid addressing problems with the systems you want to manage. These problems are caused by the address resolution protocol that returns the host short name rather than the fully qualified host name. You can avoid this by modifying the entries in the corresponding host tables on the DNS server and on the local computer system. The fully qualified host name must be listed before the short name in each entry that is associated with systems managed by IBM Spectrum Control.

The HOSTS file is in the %SystemRoot%\system32\drivers\etc\ directory. To change the HOSTS file, follow these steps:

Open the HOSTS file in a text editor.

Add, remove, or modify the host entries. In the following example of a HOSTS file, the short name is incorrectly listed before the fully qualified host name. This can cause address resolution problems in IBM Spectrum Control.

# Copyright (c) 1993-2009 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 
# space. 
# 
# Additionally, comments (such as these) may be inserted on individual 
# lines or following the machine name denoted by a '#' symbol. 
# 
# For example: 
# 
#      102.54.94.97     rhino.acme.com    # source server 
#       38.25.63.10     x.acme.com        # x client host
#
192.168.123.146       jason      jason.groupa.mycompany.com

In the following example, the order of the host names has been changed so that the fully qualified host name is placed before the short name. The host names must be entered in the order that is shown so IBM Spectrum Control can locate the host. Use this format for any hosts that are associated with IBM Spectrum Control.
```
# For example: 
# 
#      102.54.94.97     rhino.acme.com      # source server 
#       38.25.63.10     x.acme.com          # x client host 
#
192.168.123.146       jason.groupa.mycompany.com       jason
```
Note: Host names are case-sensitive. This is a WebSphere® requirement. For example, if your computer shows the name as JASON (uppercase), then you must enter JASON in the HOSTS file.