As iChain Proxy Services processes browser requests, it uses the DNS system to obtain the IP addresses of origin Web servers.
Since the DNS names in browser requests are not always straightforward, the proxy server tries various permutations to try and locate the Web server. As a result, DNS names ending with domain extensions other than .com, .org, and so on, are sometimes resolved in unexpected ways.
If users of your appliance are experiencing this problem, you can customize how the appliance resolves DNS names.
When the appliance receives a browser request, it creates a DNS query based on the URL in the request and sends the query to one of the DNS name servers defined for the appliance.
If the DNS name server can't resolve the query, the appliance formulates subsequent DNS queries based on the following:
For example, assume the following:
www.%s.com
www.%s.ed
www.%s.org
www.%s.gov
www.%s.net
%s.com
%s.edu
%s.org
%s.gov
%s.net
www.%s
After the initial request fails, the appliance formulates subsequent requests as follows:
webserver.acme.com
webserver.com
Continuing with the example, the appliance would submit the following queries, substituting webserver for the %s variable in the lines of the R_APPEND.CFG file.
Because webserver.com was tried previously, the appliance skips the sixth line (%s.com) in the R_APPEND.CFG file.
To modify the R_APPEND.CFG file:
Start an FTP client on a workstation with access to the appliance.
For help, see Starting an FTP Session with the Appliance.
Point the FTP client to one of the appliance's IP addresses.
Enter the following command:
get /etc/proxy/appliance/config/user/r_append.cfg
The file is transferred to the FTP client's default directory.
Referring to the example in How the Appliance Formulates Subsequent DNS Queries, modify the R_APPEND.CFG file using an ASCII editor.
Ensure that the lines in your file reflect the query order and content you want the appliance to use when attempting DNS name resolution. For example, you might want to reorder the domains listed or include two-letter country codes in the list.
Use the put command to place the modified R_APPEND.CFG file back in \ETC\PROXY\APPLIANCE\CONFIG\USER on the appliance.
Restart the appliance.