Website monitoring

Website monitoring is the process of testing and verifying that end-users can interact with a website or web application. Website monitoring is often used by businesses to ensure that their sites are live and responding.

Website monitoring companies that offer website performance monitoring allow businesses to simulate the actions of thousands of visitors to a website and observe how it responds. They also simulate visitors across multiple geographies and servers Internet connections. Performance monitoring tools send out alerts when pages or parts of a website malfunction, which allows the webmaster to correct issues faster.

Website Security monitoring is also used to verify that a domain (and web site) is not only responding properly, but has not been hacked, blacklisted or hijacked.

Multiple tools are available to automate site availability checks and security checks.

What for?

Monitoring is essential to ensure that a website is available to users and downtime is minimized. Users that rely on a website or an application for work or pleasure will get frustrated or even stop using the application if it is not reliably available. Monitoring can cover many things that an application needs to function, like network connectivity, Domain Name System records, database connectivity, bandwidth, and computer resources like free RAM, CPU load, disk space, events, etc. Commonly measured metrics are response time and availability (or uptime), but consistency and reliability metrics are gaining popularity. Measuring a website's availability and reliability under various amounts of traffic is often referred to as load testing.

Inside or outside monitoring

Website monitoring can be done from both inside and outside of a corporate firewall. Traditional Network Management solutions focus on inside the firewall monitoring, whereas external performance monitoring will test and monitor performance issues across the Internet backbone and in some cases all the way to the end-user. Third-party website performance monitoring solutions can monitor internal (behind the firewall), external (customer-facing), or cloud-based Web applications.

Inside firewall monitoring is done by special hardware appliances which can help you determine if your internal applications’ sluggish performance is caused by: design of applications, internal infrastructure, internal applications or connections to any public internet.

External performance monitoring is also known as end-user monitoring or end-to-end performance monitoring.

Real user monitoring measures the performance and availability experienced by actual users, diagnoses individual incidents, and tracks the impact of a change.

What impact?

If it's up...	A.K.A...	It's down... per year
90%	n/a	876 hours
95%	1σ	438 hours
99%	2σ	87 hours, 36 minutes
99.9%	3σ	8 hours, 45 minutes, 36 seconds
99.99%	4σ	52 minutes, 33.6 seconds
99.999%	5σ	5 minutes, 15.36 seconds
99.9999%	6σ	31.68 seconds

Various types of protocol

Website monitoring service can check HTTP pages, HTTPS, FTP, SMTP, POP3, IMAP, DNS, SSH, Telnet, SSL, TCP, PING, Domain Name Expiry, SSL Certificate Expiry and a range of other ports with great variety of check intervals from every 4 hours to seconds. Typically, most website monitoring services test your server anywhere between once-per hour to once-per-minute.

Advanced services offer applications that capture browser interactions with websites, as well as in-browser web transaction monitoring tools based on browser addons such as Selenium or iMacros. These services test a website by remote controlling a large number of web browsers, thus they can also detect websites issues such a Javascript bugs that are browser specific.

Time performances: for example an HTTP page should answer in less than 1 second (for a download of 16Ko) to be considered as "good".

An implementation of time performance monitoring for the Apache HTTP Server is the mod_arm4 module.

Various type of monitoring

You may monitor a single page of your website, but you can also monitor a complete business process (often referred to as multi-step transactions).

Servers around the globe

Website monitoring services usually have a number of servers around the globe - USA, Europe, Asia, Australia and other locations. By having multiple servers in different geographic locations, monitoring service can determine if a Web server is available across continents over the Internet. Some vendors claim that the more locations the better picture on your website availability while others say that three globally distributed stations are sufficient and more stations do not give more information.

Types of website monitoring

There are two main types of website monitoring

• Synthetic monitoring also known as active monitoring, and
• Passive monitoring also known as real monitoring.

Notification options - alerts

As the information brought by website monitoring services is in most cases urgent and may be of crucial importance, various notification methods, often known as "alerts" are used: e-mail, IM, regular and cell phones, SMS, fax, pagers, Skype, RSS Feed etc.

See also

• Synthetic monitoring
• Real user monitoring
• Internet Server Monitoring
• Web analytics
• Website tracking
• Application Performance Management
• Network Management
• Traceroute
• Network monitoring