It’s probobly one of the most underestimated factors in SEO, but server uptime, or rather downtime, do effect your search engine rankings. Google explained the importance of quick hosting and maximum uptime in numerous blog posts.
SEO Hosting recommend you measure your hosting speed with:
How to measure downtime?
There are a lot of services measuring downtime for free or for a low fee.
Free downtime trackers
Mon.itor.us – One of my favourite for monitoring my websites. 100 % free.
Host Tracker – Another popular website monitoring service.
Site Uptime – Monitor one web server or email account for free.
Cheap downtime trackers
–Service Uptime – For a small fee ($4.95/month), you will get notified when your website goes down.
–Pingdom – One of the most popular performance montoring services around. Start at $9.95/month.
–Web Metrics – Gives you a complete view of uptime and performance of your website.