Have you ever thought that your web hosting can ruin your search engine rankings, no? Well let me refresh your memory on how search engine ranking is being determined.
Each search engine has its own spide bot. This search engine spider bot is supposed to crawl your site, collect data (content) and store it in the search engines database. The stored data and the counted inbound links to your website based on the search engines algorithm help the search engines to determine your position in the SERPs.
So if your host is down, your site is unreachable and this means that the search engine spider bot is unable to crawl your site and store data in the search engines database. The worst case is when your web hosting server is down for too long, after several attempts of the spider bot to crawl your site he will give up and decide whether to come tomorrow and attempt to crawl your site again or after a week…ugh! a whole week without the spider bot crawling your site.