CNAME for Omntiure

What are some reasons why sites like LLNW create a CNAME record for Omniture requests (e.g. metrics.limelightnetworks.com instead of limelightnetworks.122.2o7.net)?

I've found a post that seems to suggest that it's intended to circumvent 3rd-party-cookie settings. Are there any other pros/cons to this approach? From a performance perspective, does this not create an additional DNS request from the client? Also, doesn't Omniture include a P3P header (compact privacy policty) that 开发者_运维知识库allows 3rd party cookies to be accepted by IE's default 'Medium' privacy setting?

1) https://developer.omniture.com/node/486

Here's the biggest reason why you should create the CNAME records for Omniture requests:

Friendly 3rd Party Cookies have about an 85% acceptance rate, even with IE's default setting.

The reason being that some security programs list the 2o7.net domain as a known tracking provider, and blocks those requests. Also, Safari by default doesn't accept friendly 3rd party cookies.

If you switch to a first party cookie, you'll see an acceptance rate of over 95%.