We get questions from users asking whether where we host our website plays a role in search engines. Our answer is yes there are lot of factors when it comes to ranking in search engines and a problem with a hosting company will be an other important factor.
Here are some reasons why you should select a good host.

1. Downtime: Make sure you get the best uptime not just by guarantee but by testimonials of other companies of the hosting company you want to host. We have seen most of the web hosting companies promise 99.9% uptime but a lot of them never keep up that promise. If the site goes down you have to keep going behind them and finally if there is a major fault you site might takes about 3 or 4 days which is a massive negative effect on your site. A long downtime affects your repeated customers if they are regular to your website and find you site is down for a long period eventually they will never return back which is not good for sites which depends on repeated traffic. A long downtime also affects search engine crawling googlebot and other major crawlers are programmed to visit big high quality sites on a repeated trip which varies from inbetween few hours a day to once a day to once in couple of days. If the Search engine crawlers cant crawl the site even after repeated attempts they might boot your site out of index for a short while eventually it will come back but the risk of loosing precious ranking is not good.
Also its not about repeated visitors also first time visitors will be badly affected if you have a bad hosting company and suffer a long term downtime impact in search engines. Imagine potential customers click on a search result and see that your site doesn't exist they will never come to your again.
Bad DNS resolving: I have seem some hosting companies suffer from bad DNS resolving. If the DNS resolving is not good search engine crawlers will have trouble accessing your site from some of their datacenters and a bad crawl will affect your site. A bad crawl is bad for SEO since your site should have good credible crawling capabilites for the crawlers to visit regularly and inaccessible pages on your site due to DNS problem will result in bad distribution of link juice which will cause loss of internal link popularity.
Banned IPs hosting: There are millions websites which share hosting on same Ips with other websites. Though this is a natural phenomenon sharing an IPs with too much banned websites / spam websites / adult websites will hurt your site. There is a limit no-one can prevent a bad site from being in a shared IP but imagine 60% of all websites hosted on your IP are spamming the search engines then your site will be considered part of it and this will loose your credibility with search engine algorithms.

Shared IPs: As mentioned in the above post shared Ips sometimes hurt best solution is dedicated IP but if you cant afford dedicated Ips research more on the host an if their shared IPs are fine go ahead and host.

Hosting company Search engine rankings: If you are search engine user and looking for a web host mostly you will use search. Most of the time sites that rank in top will have good credibility since they should have worked really hard to reach what they are right now.

Mod_rewrite: Though rewriting is not important now a rewrite to the dynamic URls will make search engines job easier and your users will remember URLs better. I recommend check your host first to make sure they offer good URL writing whether its PHP, or Perl or ASP

There are other factors too but above are important and can be researched before buying with a hosting company,

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