Using a DNS nameserver to locate a GRM L7 server

Using a DNS nameserver to locate the GRM L7 server

A simple GRM L7 deployment is to use a DNS nameserver to direct client requests to one or more GRM L7 servers. This deployment is best for organizations for which a simple configuration is the highest priority. This type of deployment has the following disadvantages:

GRM L7 server overload
If all client requests are sent to a single GRM L7 server, the server can easily become overloaded when the load of client requests is high. To handle overloading, you can deploy multiple GRM L7 servers and allow the DNS server to return their IP addresses to clients in a round-robin fashion.
Poor response time
There is no way to guarantee that the GRM L7 server to which the DNS nameserver redirects requests is the closest one to that client. (The DNS nameserver uses the round-robin method of load balancing.)

For example, a DNS nameserver could send a request from a client in Australia to a GRM L7 server in the United States rather than to a closer GRM L7 server in Australia. In this case, the GRM L7 server in the United States would find the GRM agent cache closest to the client. However, sending a request to the GRM L7 server in the United States takes longer than sending a request to the GRM L7 server in Australia.

The following illustration shows a deployment with a DNS nameserver directing client requests to the GRM L7 server.

The following table describes the path of the request in the previous illustration.

Stage	Description
1	The client queries its local DNS nameserver (LDNS) for the IP address of the origin server of www.netcache.com.
2	The LDNS forwards the request to the authoritative DNS nameserver for resolution.
3	The authoritative DNS server (responsible for the netcache.com domain) resolves the request and returns the IP address of the GRM L7 server (135.105.52.101) to the LDNS.
4	The LDNS returns the IP address of the GRM L7 server to the client in its response to the client's DNS request.
5	The client directs its request to the GRM L7 server whose IP address was returned by the LDNS.
6	The GRM L7 server applies its policies and other criteria to determine eligible caches and determines which GRM agent cache is closest to the client. The GRM L7 server then sends the rewritten request back to the client.
7	The client sends the request to the GRM agent cache to which it was redirected.
8	The GRM agent cache serves the content to the requesting client.