This topic has come up before in the forums but I browsed through a few of the threads and I think my situation is a bit unique. It's something I'd like to best-practice before I get too much traffic.

I currently have a site that allows users to submit content. Let's call them "articles". When they submit, it's stored in the database with a unique identifier (an auto-increment). So for example, one identifier might be 2345.

I run my site on a dedicated IP which means subdomains end up displaying the site as normal if not defined in the control panel of my host. As an example, lkdsfjasldkfj.mysite.com is essentially the same as www.mysite.com

I'm allowing users to share their article via 2345.mysite.com which then performs a permanent redirect to 2345.mysite.com/Pg.aspx?a=2345 via a script I wrote that extracts the subdomain. Realistically, it's not unfair to assume that in the future I will have pages like 893753.mysite.com. I was originally going to use directories, but I liked the "look" of subdomains and this way users get the feel that it's their own website, in a way, since they can also use username.mysite.com to display their "default" article.

My questions are:

- Is this redirect going to cause load on the server when traffic increases to tens-of-thousands of hits per day? 99.9% of the traffic will be routed through default.aspx page while doing the redirects, since it is the default page for all subdomains. If that makes sense.
- How would such a structure fare with SEO? Does anyone have any recommendations on how to improve?
- Would an Asp.net Server.Transfer work as well for SEO as the permanent redirect I am using, with Response.AddHeader? That way it would continue to remain on 2345.mysite.com with a server-side transfer instead of redirecting to the Pg.aspx page. My guess is this may be the way to go, maybe, since it's akin to URL rewriting.
- Since I'm not using real subdomains you can access the Pg.aspx?a=2345 page using ANY subdomain (except for any that are defined as real subdomains in control panel, of course). While I'm using permanent redirects, the pages are still being crawled using the www subdomain, so technically there are two live versions. Am I right to imagine this is probably bad for PR and search rank?

I just noticed this last point now. Poor planning 4tw but a breeze to fix. Thoughts?

Lastly here are examples of pages and what they do when browsed to:

www.mysite.com/home.aspx -> www.mysite.com/home.aspx (stays the same)
2345.mysite.com -> 2345.mysite.com/Pg.aspx?a=2345
username.mysite.com -> username.mysite.com/Pg.aspx?u=username

OMG I hope this makes even a bit of sense. Sorry it's so long.

Thanks everyone!
Travis