When using a CDN, the rules surround DNS records limit a user's ability to balance traffic between multiple CDN providers and or their own resources. One of the basic rules of DNS stated in RFC 1034 reads "If a CNAME RR is present at a node, no other data should be present;" This RFC limitation regarding CNAME resource records throws a wrench into any plans to deliver content from both your data centers and a content delivery providers network.

When using a traditional content delivery network your CDN provider will ask you to create a CNAME resource record pointing to a host name that they have provided you on their network.  The content delivery providers network then advertises this unique host name in their anycast network. This is how the content delivery network provider delivers your content closer to the end user.

These entries might look like this

cdn.company.com        CNAME        company.cdn.com

and the CDN providers DNS might look like

comapny.cdn.com    A    1.2.3.4

The Dynect Platform's CDN Manager is a service added to a host name on the Dynect DNS platform giving you the ability to define different resources to be used in different regions of the globe with just a few simple clicks of the mouse. We give you the ability to mix and match host names with IP addresses when defining rules on how our DNS servers will respond, then we push those rules out to the DNS clusters to help make sure that your end user is using the resource closest to them.

Using the CDN Manger allows you to alter an existing host which currently points to a single CDN provider to take advantage of aiCache. The Dynect Platform CDN Manager service editor allows you to create the service on an empty node (a node with no DNS records defined), or a node that already exists if it consists of a single CNAME resource record. 

Within the CDN Manager editor you will define a list of resource records, entering either an IP addresses or host names to populate a record pool that will be used later in defining regional rulesets. This allows you to enter in a host name provided to you by the  content delivery provider, the IP addresses of your own resource severs or an aiCache instance. If you supply an ip address, the CDN Manager service will synthesize a host name within your zone. This host name will contain the address record you supply, and the CDN Manager will include the new synthesized host in the list of CNAMEs. This full list of resource records is called the Global Pool.

After populating the Global Pool of resource records, you then define the Balancing Rules, also known as Regional Rulesets. Perhaps you have a data center and aiCache instance in California and want to use these resources to service the west coast of the United States, and use a CDN for the rest of the world. Defining regional rulesets will allow you to adjust how our DNS clusters respond to DNS queries by geographic regions. You can define a ruleset for the US West DNS cluster to response with the resources California and all other regions to use your CDN.

Regional Rulesets are defined as a subset of the Global Pool, thus giving you the ability to utilize different resources in different regions of the world. Some of those resources being your aiCache instances,  and some being that of your CDN. The Dynect Platform CDN Manager will allow you to define ruleset in seven regions (Asia, EU East, EU West, EU Central,  US West, US Central, US East). 

In addition to defining which resources should be served via DNS in each global region, you can also assign a weight to each resource in each region, with higher weighted resources being served a greater portion of the time. This allows you to control the amount of traffic received by different resources. This feature is a good way to test out new CDN providers, sending them incrementally more traffic over time.

Important things to remember: Any region not defined will be served with the global ruleset. Currently no monitoring services are integrated with the CDN Manager, but monitoring services may be defined on the host names used to populate the record pool. Combining both the benefits of the CDN Manager service with any one of the Dynect Platform's monitored services.