A good website monitoring service will do much more than simply send advice when a ocado down. The very best services will break down the response time of a web request into important categories that will allow the system administrator or web developer to optimize the server or application to offer the best possible overall response time.
Here are 5 important components of response time for an HTTP request:
1.DNS Lookup Time: The time it takes to find the authoritative name server for your domain as well as for that server to resolve the hostname provided and return the appropriate IP address. If this type of time is simply too long the DNS server should be optimized in order to provide a faster response.
2.Connect Time: This is the time required for the web server to respond to an incoming (TCP) socket connection and request and to respond by creating the connection. If this describes slow it always indicates the operating-system is trying to reply to more requests than it can handle.
3.SSL Handshake: For pages secured by SSL, the time has come required for both sides to negotiate the handshake process and hang up up the secure connection.
4.Time and energy to First Byte (TTFB): It is now time it takes for the web server to reply with the first byte of content following the request is sent. Slow times here almost always mean the internet application is inefficient. Possible reasons include inadequate server resources, slow database queries and other inefficiencies associated with application development.
5.Time to Last Byte (TTLB): It is now time needed to return all of the content, following the request has been processed. If this sounds like taking a long time it usually indicates that the Internet connection is just too slow or possibly overloaded. Increasing bandwidth or acquiring dedicated bandwidth should resolve this problem.
It is extremely challenging to diagnose slow HTTP response times without all this information. Without the important response data, administrators are still to guess about where the problem lies. Lots of time and money can be wasted attempting to improve different pieces of the web application with the aspiration that something will continue to work. It's possible to completely overhaul an internet server and application only to find the whole problem was actually slow DNS responses; a problem which exists over a different server altogether.
Use a website monitoring service that does a lot more than provide simple outage alerts. The most effective services will break the response time into meaningful parts which will allow the administrator to identify and correct performance problems efficiently.