About a GRM DNS server

How a GRM DNS server performs redirection

A GRM DNS server provides standard DNS redirection plus a layer of intelligence that is not available with standard DNS, including support for proximity measurements, detection of unavailable GRM agent caches, and filtering. As with standard DNS, the client's local DNS nameserver communicates with the GRM DNS server through a DNS request, and the GRM DNS server responds with a DNS response.

The GRM DNS server returns to the client a list of IP addresses of the available GRM agent caches that are close to the local DNS nameserver that the client uses. The client browser then selects a GRM agent cache from the list returned by the GRM DNS server. The GRM agent cache that the browser selects might or might not be the closest cache to the client.

See Section A, Deployment with only a GRM DNS server and Using a GRM DNS server to locate a GRM L7 server for deployment examples.

Relationship to the back-end nameserver

A GRM DNS server can assume the identity of the existing authoritative DNS nameserver for the CDN name space; that is, the GRM server can assume the IP address that was previously assigned to the authoritative DNS nameserver. The authoritative DNS nameserver is then reconfigured with a new IP address. The authoritative DNS nameserver becomes the back end to the GRM DNS server in this case.

When you need to include a GRM DNS server

Deploying a GRM DNS server is appropriate in the following circumstances:

When local DNS nameservers are close to clients.
See Section A, Deployment with only a GRM DNS server for a deployment example.
When you are deploying GRM L7 servers and you want to use a GRM DNS server to direct client requests to the GRM L7 servers.
See Using a GRM DNS server to locate a GRM L7 server for a deployment example.