ARL syntax

The primary function of an ARL is to direct an end user’s request for an object to the ​Akamai​ network. The ARL also contains the object’s caching properties.

Example of an ARL

ARL syntax exampleARL syntax example

Serial number

Serial numbers balance the distribution of content on the ​Akamai​ network

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The serial number appears in two places in the ARL and should be the same in both fields.

​Akamai​ domain

  • Non-secure (HTTP) content: a<serial_number>.g.akamai.net.
  • Secure (HTTPS) content: a248.e.akamai.net.

Typecode

Indicates to the ​Akamai​ edge servers the type of coherence mechanism to be used for each object. The two most common options are typecode 7 and typecode f.

7

Typecode 7 indicates that the Object Data field contains an Object ID.
When an ​Akamai​ server first caches an object, it creates an identifying entry for the object that contains the object’s source URL and the Object ID, for example 200201171350 - www.foo.com/images/logo.gif. If either of these ARL fields changes in a subsequent request, the ​Akamai​ server retrieves the new version of the object from the origin server.

f

Typecode f indicates that the Object Data field contains a TTL value.
The TTL instructs the ​Akamai​ servers to send a periodic If-Modified-Since (IMS) GET request to the origin server to verify that the object is still fresh. Valid values for the TTL are [number][s,m,h,d]. For example: 30s, 15m, 5h, 30d.

Customer code

Identifies the content provider and is used for billing and reporting.

Object data

Serves as a coherence or object-freshness mechanism. Depending on the typecode, it contains either an Object ID or a TTL.

URL (absolute)

Specifies the origin or source URL of the object. It is the location from which ​Akamai​ servers retrieve the object to cache or refresh it.

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Any domain used in an ARL must be registered through the ​Akamai​ Domain Validation tool. If the ARL of an object contains an unregistered domain, ​Akamai​ servers will not serve the object.


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