Configuring a Content Delivery Network
3-DNS® Administrator Guide 7 - 9
Now you have created a topology statement for your CDN, and the 3-DNS
Controller can successfully load balance DNS queries based on the location
information derived from the DNS query message. For our example, using
the topology statement you just created, the 3-DNS Controller would direct
queries for www.download.siterequest.com that originated in North
America to the origin pool for resolution. Requests that did not originate in
North America would be directed to the CDN provider using the cdn_ pool.
Ensuring resource availability
The following resource availability settings are designed to ensure that your
content is always available and that your system resources are not overtaxed
to the point of failure. The resource availability settings you may want to use
with your CDN configuration are:
◆Last resort pool
You can designate a pool as the last resort pool so in the event that all
other pools become unavailable for load balancing, the 3-DNS Controller
can direct DNS queries to the virtual servers in this pool. For information
on configuring a last resort pool, see Using the last resort pool
designation in Chapter 2, Load Balancing, in the 3-DNS Reference
Guide.
◆Limit settings
You can set limits on system resources and throughput to enhance
availability. You can set limits for any server type, virtual servers, and
pools. For more information on setting limits, view the online help for
the Modify Limit Settings screens in the Configuration utility.
◆ECV monitor
With an extended content verification (ECV) monitor, you can verify that
a specific file is available on the content servers for a wide IP. For more
information on ECV monitors, refer to Working with the ECV service
monitor, in the 3-DNS Reference Guide, Chapter 2, Load Balancing.