How do sites avoid SEO issues and legalities with subdomain unique ids?

Question

I was looking through a few websites recently and noticed a trend I am not sure I understand. Sites are creating unique referral URLs for customers in the form of: http://customname.example.com

(If somebody were to use http://www.example.com/customname it would function the same way).

I can see the sites are using 302 redirects at some point using Google Chrome then doing some sort of htaccess redirect, taking the sub domain name (custom name) and applying it as a referral parameter then keeping in session during the entire process.

However, there must be thousands of these custom URLs that people are typing in. How are each one of these "sub domains" not treated as separate URLs which in turn are redirected to the same page (in short, generating tons of links all pointing to the same page which Google would normally frown upon)? Additionally, the links also appear on the site themselves as click-able links so I'm not sure how these are not tracked. Similarly, the "unique" URL is not indexed or cached in any Google search results.

How is this capability handled?

1. I know these are 302 redirects, I can see this on the sites network flow.
2. These links do in fact appear on the page itself because in some areas, for example, the bottom of the page may say: send this page to a friend! http://name.example.com/ which in turn would again redirect to something like http://www.example.com?id=name so the id value could be stored in session

Answer 1

There are not legality issues. Here is how it it breaks down:

From SEO Perspective All content on Site.example affects the score. So Site.example/User/Frank affects the score of site.example. frank.site.example is treated by Google as a separate site. Gets its own Google page rank.

So here is the rule. If you are running something you want indexed separately then use a subdomain. A good example if you have a web application that builds sites for users. Frank.myfreesitecreator.example or bob.myfreesitecreator.example. Then Frank could point a FQDN (domain name) to frank.myfreesitecreator.example and worry about his own SEO score.

If you have a site where you want everything indexed in one big ball, then use URL folders. 302 redirects help Google understand what is going on. That is it. Google will index the final result.

Answer 2

Similarly, the "unique" url is not indexed or cached in any Google search results. How is this capability handled?

Maybe the webmaster has excluded them, either with robots.txt or through Google Webmaster Tools.

Additionally, the links also appear on the site themselves as clickable links so I'm not sure how these are not tracked

Maybe... rel="nofollow"

And finally, the 302 redirect is passing the "juicy" to the main site.