Internet server monitoring
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Internet server monitoring is much wider than website monitoring. Monitoring a web server means that the server owner always knows if one or all of his services go down. Web server monitoring may be internal, i.e. web server software checks its status and notifies the owner if some services go down, and external, i.e. some web server monitoring companies check the services status with a certain frequency. External monitoring is much more reliable, as it keeps on working when the server completely goes down.
Web server monitoring service can check HTTP pages, HTTPS, FTP, SMTP, POP3, IMAP, DNS, SSH, Telnet, SSL, TCP, PING and a range of other protocols with great variety of check intervals from every 4 hours to every one minute. Typically, most website monitoring services test a server anywhere between once-per hour to once-per-minute.
Web server monitoring process
When monitoring a web server for potential problems, an external web monitoring service checks a number of parameters. First of all, it monitors for a proper HTTP return code. By HTTP specifications RFC 2616, any web server returns several HTTP codes. Analysis of the HTTP codes is the fastest way to determine the current status of the monitored web server.
Common Web Server Monitoring Services
As the information brought by web server monitoring services is in most cases urgent and may be of crucial importance, various notification methods may be used: e-mail, land-line and cell phones, SMS, fax, pagers, etc.