links that definitely have a problem
	links that perform OK but are inefficient
	links that were unable to be checked

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Common Alarm. This alarm is known to occur when the file requested has not been uploaded to your server correctly. An empty file may exist on your server, but has the correct filename.

What you can do: If it is an HTML file, upload it to your server again ensuring the file transfer protocol used is TEXT. If it is a graphic or program file, upload it again ensuring the BINARY protocol is used.

Rare Alarm. Occasionally seen submitting FORMs.

What you can do: Check that the form operates as expected with your back end system.

Rare Alarm. This alarm is sometimes seen on sites that restrict access to certain content to valid users coming through a proxy server. Usually, publicly available content should not be pointing to these resources.
What you can do: Change/remove/append security restrictions according to your requirements.

Common Alarm. The link as specified in your HTML document is not formatted properly. When presented, the responding server cannot process it.

What you can do: Check for illegal characters in the URL and ensure SRC and HREF elements use quotation marks. Spaces are not allowed in URLs. Look out for curly quotation marks. Make sure your HTML editor uses ' and ".

Common Alarm. The file requested requires a username and password for delivery. Commonly seen where content from an intranet has been made publicy available on the public internet.

What you can do: Check that the file should be password protected, remove protection if necessary. LinkAlarm can check password protected sites when you specify the username and password on the Site Control : Password Access page.

Rare Alarm. As e-commerce evolves on the internet more servers will use this alarm.

What you can do: Sit back and relax, be confident in your abilities and exepect the unexpected.

Common Alarm. The server will not provide the requested file. Commonly seen where content from an intranet has been made publicy available on the public internet or when your link points to a directory on a server and that server is configured to not provide directory listsings.

What you can do: Remove protection or provide and index file in the directory if necessary.

Very Common Alarm. The file specified in the URL does not exist.

What you can do: Is the file you are pointing to still in the same place? Try getting the directory listing for that file to see if it is still here. Make sure the case of your URL is the same as that on the target server. Most servers treat "/directory/file.html" differently to "/Directory/File.html". Find the correct URL by searching the target site or asking the webmaster there. Or use a search engine to find a similar file. Remove the link from your content if it cannot be found.

Common Alarm. Most commonly seen in ACTION links on FORMs where the server has not been configured to allow POST operations.

What you can do: Enable the ACTION for the correct location in your server configuration.

Rare Alarm. Either the document you have requested does not exist, or it exists but not in a format that can be displayed.

What you can do: Check the link manually in a browser. Contact the LinkAlarm Help Disk if required.

Rare Alarm. The server providing the file you're pointing to will deliver it only via a proxy server to users providing a username and password.

What you can do: Verify the security requirements of this file and modify security access if required.

Common Alarm. LinkAlarm waited 120 seconds before giving up trying to retrieve the file. Either the server was too busy, or down or the network between LinkAlarm and the target server was down.

What you can do: Re-check the pages with alarms. If the same links yield the same errors, consider testing some of them manually. If unreliable access continues, condsider removing the links from your content.

Rare Alarm. Seen in custom systems using file upload (PUT) features.

What you can do: Test the system manually for correct operation.

The provider of the remote content has decided to mark the file you're pointing to as gone forever.

What you can do: Remove the link from your content, or ask the remote webmaster if there is a replacement.

Rare Alarm.

Rare Alarm. Sometimes used when validating FORM input on the server.

What you can do: Test the FORM manually. LinkAlarm cannot submit your forms with pre-determined data, sorry.

Rare Alarm. Access restrictions on the target server disallow retrieval of that file. The file may have been uploaded incorrectly or may be corrupt on the server, providing garbage data to the web serving program.

What you can do: Ensure the server configuration matches the expected size requirements of your content. If necessary, replace the file in question and re-check the pages with alarms from your control panel.

Rare Alarm. Seen when a FORM dynamically builds a link to a CGI program based on user input.

What you can do: Test the FORM manually using the maximum data allowed in each field. Modify client-side validation to ensure URLs submitted are not too big for the target server.

Common Alarm. The file extension specified in your URL is not handled by the server.

What you can do: Configure the MIME types on the server to deliver the file in the appropriate way.

Rare Alarm. Seen in custom systems validating values in FORM submissions.

What you can do: Check the system manually to ensure the values that can be entered in the FORM match the CGI program requirements at the server.

Rare Alarm. The server expected a specific header when processing the link.

What you can do: Check the system manually to ensure the link submitted matches the CGI program requirements at the server.

Common Alarm. The link, possibly in a FORM, is not able to be processed by the target server.

What you can do: Ensure the FORM ACTION and METHOD are correct for the service in question. Test the link manually in different browsers.

Common Alarm. Usually the result of a mis-spelled URL or host name. Possibly a transient network failure.

What you can do: Test the link manually or verify the spelling of the hostname in your URL. Re-check the pages with alarm to determine if this problem is permanent. If so, consider dropping the link from your content.

Rare Alarm. Occasionally seen in links to prototype servers and custom systems.

What you can do: Check that the link works in a browser. Ignore this Alarm if you are confident browsers can access this resource reliably.

Common Alarm. A "file://" URL was encountered and could not be checked. "file://" URLs point to documents on your disk drive or local area network. File URLs sometimes get added in the editing process when dragging and dropping content from your desktop to your HTML editor.

What you can do: Ensure your HTML editor and the location of your source HTML files are configured correctly.

When you view your web site which has a for an image, you may see the image in your browser anyway as it is delivered to your browser from your disk. Only people who have access to the same filesystem will see the image.

Common Alarm. The host name specified in the URL is not correct. The public domain name system does not have knowledge of this host name. Sometimes this occurs when intranet content has been moved to the public internet. The links in the content may not contain fully qualified domain names, rather just hostnames that resolve only on the intranet.

What you can do: Ensure the correct hostname is specified in the link. Use fully qualified domain names (http://www.host.com/file.html not http://www/file.html).

Rare Alarm. Occurs where a link points to a custom CGI program, requiring special interraction.

What you can do: Check that the operation of the CGI and surrounding pages works as expected.

Rare Alarm. Occurs in custom server configrations and electronic commerce systems. Some servers use this status code to change to HTTP 1.1 for more efficient communication.

What you can do: Ensure your server is correctly configured for content negotiation. If a CGI program produces this response, make sure the program is authorized to be operating on your server.

Rare Alarm.

What you can do: Check the associated pages and CGI programs. If your CGI program is processing data from other systems in real time ensure you are returning a correct status code.

Rare Alarm. This response is provided in custom CGI programs.

What you can do: Ensure your CGI program is supposed to be supplying partial content.

Rare Alarm.

What you can do: If the URL returning this alarm is on your server, make sure your server is configured correctly for content and language negotiation. If it is not on your server, make enquiries with the remote webmaster/site developer to verify this is the expected response.

Common Alarm. The file requested has been moved to a new location. Modern servers and browsers handle this condition by redirecting the browser to the correct location. This is inefficent and slows down the browsing experience for your viewer.

Configuration of "Moved" status codes is usually accomplished at the server. 301 Moved Permanently and 302 Moved Temporarily seem to be used interchangeably to handle content that needs to be re-organized.

What you can do: Change your link to point to the new location.

Common Alarm. The file requested has been moved to a new location. Modern servers and browsers handle this condition by redirecting the browser to the correct location. This is inefficent and slows down the browsing experience for your viewer.

Configuration of "Moved" status codes is usually accomplished at the server. 301 Moved Permanently and 302 Moved Temporarily are used interchangeably to handle content that needs to be re-organized.

What you can do: Change your link to point to the new location.

Rare Alarm. A more common way to redirect the browser to a new location following a POST operation is to return a Location: URI header.

What you can do: Change your link to point to the new location if necessary.

Shown here for reference only. Servers and proxy servers provide this result when the browser already has the current version of the document.

What you can do: Relax, and enjoy the fact that getting that document did not waste server computing cycles and network resources.

Rare Alarm. This alarm is temporary by nature and should not be present on subsequent LinkAlarm site checks.

What you can do: If you continue to find this link is redirected, contact the content owner and see if you should change your link.

Rare Alarm. This alarm is aparrent in online database systems and other special situations where content is created as a response to information provided by the user. In general, using scripts to create content on the fly should require POST operations that validate form fields - this should not be done with GET requests on your server.

What you can do: Ensure the link that reports this alarm is configured correctly. Check the system for correct operation in a browser. If it is your CGI, you probably shouldn't be creating resources on your server when the program is HEADed. If all is well, you may Ignore this alarm so it is not reported in the future.

Rare Alarm. Sometimes returned by custom CGI programs.

What you can do: Ensure your program and corresponding web pages are working by checking manually in a browser.

Common Alarm. The server was not able to process the link.

What you can do: Check the link manually while examining the server log file (if possible). Make modifications to the server configuration as required. If the link points to a remote server, contact the webmaster to notify them of the problem. Consider removing the link from your content if unreliable access to this server persists.

Common Alarm. The server was down, or the network from LinkAlarm to the server was not operational at the time of checking. LinkAlarm will check a server 3 times over the period of checking, waiting 120 seconds each time.

What you can do: Re-Check the pages with alarms. If this condition persists, verify the link manually. Consider dropping the link from your content if unreliable access persists.

Common Alarm. The server was down, or the network from LinkAlarm to the server was not operational at the time of checking. LinkAlarm will check a server 3 times over the period of checking, waiting 120 seconds each time.

What you can do: Re-Check the pages with alarms. If this condition persists, verify the link manually. Consider dropping the link from your content if unreliable access persists.

LinkAlarm could not connect to the specified service from the public internet at this time.

What you can do: Test the server link manually in a browser. Test from a different location to see if a firewall is preventing access.

Common Alarm. Access to this server was forbidden to robots (like LinkAlarm) by the presence of a "robots.txt" file. Content providers limit access to indexing and searching robots for various reasons.

What you can do: Turn on the Site Control : Forbidden Access and recheck the pages that showed alarms.

Ignore the link if you are happy it is functional.

Check the link manually in a browser.

Contact the webmaster of the server to allow access to the LinkAlarm checking robot by asking them to adding the following lines to their robots.txt file:

User-agent: LinkAlarm  
Disallow:  

 

Web server error codes are specified in HTTP 1.1 RFC 2616