How do you forward traffic to a site whose name can't be resolved by DNS

Products

• Asset Management Solution
• ProxySG Software - SGOS

Issue/Introduction

Proxies can be deployed to sites whose DNS can't resolve a hostname that is required by clients.  If the hostname of this site resolves to a single IP address and it does not change often, policy can be written to forward requests to the IP address of the  hostname.

Resolution

The following policy will

 

1. Prevent the proxy from doing a DNS lookup for the site, since the DNS lookup will fail.

2. Take all traffic bound for the site and forward it to the site.

The following policy is done for the site https://validation.es.bluecoat.com which resolves to 199.91.133.45.  Replace validation.es.bluecoat.com and 199.91.133.45 with whatever site you are working with.

1. Go to Configuration>Forwarding and configure a host with the alias bluecoatvalidation, host 199.91.133.45, Ports are HTTPS 443
2. Go to Configuration>Policy>Policy Files>install local file from, choose Text editor.  Add the following policy to the end of the file:

restrict dns
    //validation.es.bluecoat.com 
end

<Forward> 
    server_url.host=validation.es.bluecoat.com forward.fail_open(no) forward(bluecoatvalidation)

At this point all requests to validation.es.bluecoat.com should be forwarded to alias bluecoatvalidation.