There are two key points to how search engines get information about your site. You can use this information to update your site at the correct times and avoid downtime at the worst possible times.

First they crawl, then they index. Crawling is done by spiders (or also called robots) that automatically view all content & follow links on your website.

While crawling involves exploring your site and indexing is saving that data on their servers for quick retrieval. Many web servers track when your site is visited by a spider.  If you don’t have that insight into your log files, you can get the information in a roundabout way following these quick steps:

1. Search for your site.

2. Click on the link that says “Cached”

3. View the date & time of the last crawl at the top of your framed in page.

Bing shows this as well:

So now that you know how to find when your site was crawled, create a simple spreadsheet to keep track. Get a good idea of frequency and you will know the best times to update your content, make server upgrades or any other changes you have planned.