Re: known request routing

[Eric Dean <eric@crystalballinc.com>]

Comments:

Section 2.8.5: There are some implementations of DNS that forward the client's IP 
address within the DNS packet's "Additional" section.

Section 4.2.3: Raises security concerns and may have problems with zipped/encrypted 
content.

I also notice that there are "Pure" DNS-based request routing methods and then there 
are those that have a DNS+URL based method.  A distinction is that a Pure DNS method 
allows for caching surrogates to run in a native mode for it's internal and peered 
CDNs.  By this, I mean that it can serve content regardless of the origin server.

A DNS+URL based mechanism that encodes specific CDN control information after the 
FQDN (in what would appear to be the absolute path), such as http://cdn.foo.com/cgi-
bin/foo/img.gif... would have difficulties interoperating with other caching 
surrogates that apply only native request logic. 

Section 6.2.1: You may also want to highlight that probing techniques often only 
probe the client DNS server and not the client.  Also, while probing only occurs 
periodically, client DNS servers remain relatively immobile.
--
Eric Dean
President, Crystal Ball Inc.
W 703-322-8000
F 703-322-8010 
M 703-597-6921