Who has produced the site? – Site ‘ownership’ may affect the validity of the information – what is the information being displayed for?
How relevant is the information? Careers information from US based sites may be of limited use. The nationality of a site may not be immediately apparent
How recent is the information? Especially for career pages you should look to see when the site was last updated.
Please see these links for information on both careers and higher education.
Other useful websites