One of my monthly maintenance tasks for my client's websites is doing a quick linkcheck. I've been coming across a number of issues with links to external sites. My client's create links to sites that are relevant to their visitors and the links provide additional information to their visitors, I encourage them to check any links created to make sure they work, which they do - all good and dandy. How come my linkcheck still shows up loads of broken links?
Because the sites linked to aren't implemented properly. An example: the client linked to a page in the news section of a site with multiple languages. The link check showed up an error. I visit the site to find out what's wrong with the link and see a 404 page not found in Russian (go ahead and try it yourself). So I click on the English flag and go to the news section again. Turns out the page does exist and works, but only after visiting the English homepage first. I do some more experimenting and add try adding en/ to the URL http://www.sgp.uz/en/news/161 (as that works in mosts sites) and presto it works even without visiting the homepage.
Sites interlinking are one of the building blocks of the internet and a major factor with search engines. I would therefore assume that you would make it easy for visitors to link to your site.
Lesson learned: do not require cookies for navigation through your website as search engines do not accept cookies and links to your pages may not work!