Sam Ford, a fellow blogger from the Marketing 150, reached out to us about their new domain:
I wanted to quickly ask if you could change the URL for the Convergence Culture Consortium. We recently changed our URL to http://www.convergenceculture.org/weblog/, and I wanted it to be fixed on your list. Thanks!
No problem, done. (Good luck with the new domain, Sam!)
But there's something wrong about this request -- a site owner shouldn't have to be reaching out to all of their inbound links to tell them about a change. Their server should be handing out 301 redirects to let visitors know of the new location.
This laissez-faire domain configuration could harm rankings in search engines through duplicate content penalties. Yes, the search engines should be able to cannonicalize these domains, but you're better off it doing it yourself by issuing hard redirects (301s) from the three "wrong" (www-net, no-www-net, no-www-org) domains over to the one "right" domain (www-org). Easy -- takes just a few minutes tweaking the server config.
Properly handling URL structure changes (vs. just domain changes) takes more time and care.
For example, suppose you want your "jobs" page to move from "www.yourdomain.com/jobs" to "www.yourdomain.com/careers". All fine and good. Just use a 301 redirect to tell visitors about the change. What you don't want to occur is a broken link (the server sends a 404 "not found" to when asked for "/jobs") or duplicate content (the server sends the same page to both requests).
The W3C instructs, "don't change URLs", but often that solution isn't feasible. You can change URLs, but you need to do it carefully and keep the old forms working.
Consider every URL on your site a promise or a contract: a search engine can index that URL (unless you've no-indexed the page), a human can bookmark it, a scraper can rely on it, etc. When you migrate a site to a new URL architecture, make sure every old URL still works. Mishandling your old URLs is linkrot, which degrades both your site, your rankings, and the entire web.
Like with a domain change, the right way to handle URL changes is through 301 redirects, which tell visitors
"Hello! You were looking for a page at X, and now it lives at Y, and this change is permanent, so please update your records and next time come in directly to Y for it."
Properly handling URL changes often isn't as easy as a simple server tweak. Unless the new and old URLs differ by a common regular expression, it is likely you'll have to create extensive explicit old-to-new URL mappings.
Inbound links are precious. Not only do they matter to search engines, but they reflect the interconnected relationships of pages and people and ideas on the web.
When reorganizing your site, don't break the old links. Redirect visitors to the new URLs.