Subdomain 301 rules?

Subdomains and 301

[Steph_R]

I have example.com setup with a 301 redirect to www.example.com

My question is this...I have several subdomains. Do I also need to set them up with a 301 redirect so that sub.example.com redirects to www.sub.example.com?

I would prefer not to, but if it is necessary I will.

[pinterface]

No. In fact, the example.com -> www.example.com redirect isn't strictly necessary, though there's certainly nothing wrong with having it. However, you might consider redirecting www.sub.example.com to sub.example.com, to catch people who automatically add www to every domain name they see.

www isn't special. It's just a subdomain like anything else, and might as well be web, foo, or schnuppelutz--there's no technical difference between them.

[jdMorgan]

> I have several subdomains. Do I also need to set them up with a 301 redirect [...]?

That depends on whether you use those subdomains for separate sites or not. If they all resolve to the same site as example.com and www.example.com, then you risk loss of ranking [webmasterworld.com] from the the so-called 'duplicate content penalty' mentioned in this recent thread [webmasterworld.com].

If you use your subdomains to host unique content, then of course you wouldn't want to redirect them and lose that content.

Jim

[Steph_R]

www.example.com and sub.example.com each have different content, and are hosted on different IPs.

In G, will www.example.com get "credit" for the content on sub.example.com (even with no 301 on sub.example.com)?

The more unique content, the better? Correct?

Thanks for your help.

[jdMorgan]

If they're separate sites, then they're separate sites, so you'd certainly *not* want to redirect them. If you did, then their content would become inaccessible on the Web.

The problems discussed in the other threads arise when hosting companies allow the same site to appear when requested via http://www.example.com, http://example.com, and also with the URL http://192.168.0.1 (where this IP address represents the site's real IP address). That's three ways to address the exact same pages, and that can cause the trouble previously discussed in those other threads.

There's also the case where a site implements 'wild-card' subdomains, but includes no check for unused or undefined subdomains, instead pointing them all to the main site.

In these cases, you get the same pages appearing in multiple domains. This allows other Webmasters to (accidentally or intentionally) link to your site in several different ways, splitting your PageRank and Link Popularity across multiple domains. In the first thread cited above, this was done by a malicious Webmaster to intentionally damage the ranking of the site belonging to a client of the person who posted the thread.

I don't know of any way to make it clearer, other than to say that each of your pages should appear on one domain and one doamin only, and any 'doppelgangers' appearing on any other domains should be 301-redirected to the corresponding page on the canonical domain for that page.

Jim