Everyone will understand that broken external links will lower the user experience.
Not everyone will know that the percentage of broken links at your website is an indication for search engines how often you check for broken links.
A lot of broken links? Poor maintenance!
The halftime of an external link is two year. Hence the number of broken links indicates what was the last time you checked and repaired broken links.
Repairing broken links at a regular base is the difference between a neglected site and a smooth website.
Redirected links are dangerous
Almost everyone thinks that redirected links won't do any serious harm. Believe me that is a huge mistake. Redirected links are dangerous.
Recently I analyzed the reason why links are automatically removed from ZOMDir.com (you will find the numbers below).
One of the main findings is that one percent of the removed links, link out to hacked sites.
How to find links to hacked sites?
Almost the only way to discover links to hacked sites, is by following the redirected link. When you see an online shoe store where you expected information of a fitness center, you know the site is hacked.
Of course there are a lot of redirected links. A lot of websites switch from http to https these days. Make live easier for yourself and link to the redirected site instead of the original site. Otherwise you have to check every redirected site again and again when you check and repair broken links.
Other findings
1. Half of the broken and redirected links could be fixed. That is the target website is still working fine, although the website has been rebuild. Depending on the quality of the rebuilding team you are redirected, get a neat 404 error or a brute server error;
2. Ten percent of the broken links are due to programming errors. This vary from very slow loading webpages, to pages without any content, to incorrect database connections. So always check your entire site with a broken link checker when someone has changed something at your site;
3. Another ten percent of broken links are due to the classic 404 page not found error. Most of the time these error indicates that the website was rebuild, and the rebuilding team didn't redirect the old webpage;
4. When a site owner gives up a domain name, around 25% of these old domains are parked by a domain broker;
5. 30% of the removed links are removed due to redirections. Nearly all redirected webpages redirect to a secure site.
Raw research results
Here are the raw results of my research.
Error codes broken links
ZOMDir has an inbuild linkchecker (similar to "Broken Links at a Glance") and ZOMDir keeps track when and why a link is removed.
I analyzed the last 5000 removed links. These links where removed from July 30, 2016 till July 16, 2018.
On average every day 7 links are removed at ZOMDir.com.
Manual removed links
These links are removed by hand. Probably because these links were added to an inappropriate category.
Manual 408 8%
Server side errors
Error 500 2361 47%
Error 503 169 3%
Error 502 10 0%
Error 504 1 0%
Redirections
Error 301 1027 21%
Error 302 374 7%
Error 303 25 1%
Client side errors
Error 404 479 10%
Error 400 30 1%
Error 401 30 1%
Error 402 20 0%
Error 403 18 0%
Error 410 16 0%
Security errors
When ZOMDir checks broken links, there is also a check if the page linked to is still safe to visit. When that's not the case you will get a 604 error.
Error 604 32 1%
Manual checked links
By hand the latest 564 removed links where checked. The formal error codes aren't that relevant now. I want to know indepth why a link was removed. Here are the findings:
Server not found 149 26%
Temporary error 110 20%
Redirected 101 18%
Page not found 76 13%
Domainparking 45 8%
Programming error 32 6%
Slow website (no response) 19 3%
Stop of freehosting 15 3%
Site in maintenance mode 10 2%
Hacked 7 1%
Thanks, for your attention, happy linking and please check and repair your links at a regular base.
Hans
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ZOMDir.com is a dynamic directory and a wiki
Everyone is able to add a link in 10 seconds
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