Here you can read about what a server is and see examples of server responses and what server factors to look for
Server Tips for Servers and Configurations
Unfortunately, just having a domain pointing to a web server is not enough to be sure of good opportunities to appear in search engines. In addition to this, it is important how a server behaves.
Examples of server responses
When a server receives a call, it responds to various so-called HTTP codes. Different HTTP tags mean different things for a web browser, but also for a visitor and indexing web spindle. For example, HTTP 200 means OK, after which a page's content is displayed. HTTP 404 means that the requested item could not be found, after which the 404 response becomes a dead end. In a thorough SEO work, it is important to have a clear strategy for managing different such status codes in order to maintain the greatest possible relevancy and link power without compromising the user experience on the site. » List of HTTP Status Codes (Wikipedia)
Avoid indexing issues
In order to avoid duplicate content problems , your web server should only respond to a single address per page. At addresses other than the specific one, it is best to let the server respond with a so-called HTTP 301 ( 301 Redirect ), which is a permanent reminder. Most common is that the method is used to declare that the same pages can be accessed via and without www, for example, that the same page is displayed on both example.com and www.example.com .
Additional server factors
In addition, a server should be stable and have good "uptime" - thus be available and not "lie down". They should also be quick and readable, especially since site speed has been introduced as another ranking factor with Google and a slow server may well adversely affect your keyword optimisation .