Symptoms, types and causes
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Symptoms of a website failure
The browser cannot find the page - this is a problem with the domain (e.g. expiry) or DNS server.
Timeout - it seems that the page is loading but it takes a lot of time and nothing is displayed.
Error message - the server displays a three-digit error number and its description (see Server Error Codes below).
The page is displayed incorrectly - e.g. some content or images are missing or everything is shifted.
Functionalities do not work - e.g. a contact or registration form.
Types of website failures
Network failures - the page is unavailable because of a link failure. This refers mainly to the links on the internet server side.
Problems with other links - between operators and on the user side - make the website unavailable only for some users and are not treated as a failure.
One of the network failures is also the DNS server configuration error.
Hardware failures - website unavailability is caused by damage to one of the server units, e.g. the hard disk.
One of the hardware failures is also the data centre failure, e.g. a power supply failure.
System failures - website malfunctioning results from misconfiguration of the server, its operating system or the installed software.
One of the system failures is also the failure connected with databases.
Application failures - errors in the construction of the website itself causing its malfunctioning.
Efficiency failures - the traffic exceeds the infrastructure (server and link) capacity and the page cannot be displayed to all users.
This most often signifies an unexpected surge in the website’s popularity.
Server error codes
The most common http error codes and their meanings.
401 Unauthorized - authentication has failed or not yet been provided.
403 Forbidden - the request was a legal request, but the server is refusing to respond to it.
404 Not Found - the requested resource could not be found but may be available again in the future.
500 Internal Server Error - a generic error message, given when no more specific message is suitable.
502 Bad Gateway - the server was acting as a gateway or proxy and received an invalid response from the upstream server.
503 Service Unavailable - the server is currently unavailable (because it is overloaded or down for maintenance).
Causes of website failures
Human error - the root of application and system errors and less frequently hardware errors.
These are unintentional failures which are most easily repaired.
Random - impossible to be foreseen, e.g. a failure of a new hard disk from a renowned producer.
These also result from natural catastrophes, burglaries where hardware is stolen etc.
Intentional - these are usually planned shutdowns where it is impossible that each and every user is informed.
However, these are also hacker attacks.
Hardware wearing out - mechanical elements (e.g. traditional hard disks) have a limited life cycle.
As is the case with people - some die earlier and some die later.
Results of website failures
No sale made - financial consequences of a failure are most evident in the case of e-commerce websites.
Lost leads - potential clients will not wait and will go to the competition.
Wasted budget of the campaign - the money spent on the advertising goes down the drain when the users do not land on a working website.
No ads displayed - the website which earns through advertising will earn less when no adverts are shown during the failure.
Dissatisfied clients - if an online customer service fails, even the most loyal clients may desert.
Damaged image - a failing website will be noticed by journalists, partners, providers and employees.
Consequences for SEO - search engines may downgrade the website in the rankings, if it is often unavailable.
Operational problems - if any business processes are run through the website, negative effects may affect various aspects of company operations.