How long after google crawl do you need 301 redirects

[Paul_MC]

We have just added 301's when we moved our site. Google has done a crawl & spat back a few errors. How long do I need to keep those 301's in place? I may need to change some. Thanks

[TakeshiYoung]

Google will continue to crawl your old URLs as long as links to them exist, so you will want to keep those 301s in place for as long as those links exist. Does that make sense?

It's not that Google will crawl a URL, see that it is being 301'd and never crawl that URL, Google will continuously crawl that URL as long as it is being linked to, and you need to have the 301 in place to tell Google that the page has moved.

[Paul_MC]

Thanks for the quick response. Basically, we changed from a hosted solution to magento & needed to redirect all of our old url's to the magento URL structure. I guess what I need to know is, once google has crawled & found the 301, does it then ignore the 301 in future (as it already knows it has been moved)?

[TakeshiYoung]

You need to keep those 301s in place as long as you have links pointing to the old site that you want to get credit for. If you can contact the owners of the sites that are linking to your old site and get them to change the links, you can remove the 301s. Otherwise you will want to keep them in place.