Check out the publisher's web site to see what type of material they produce. Give preference to information from government agencies, trade and professional associations, major universities or organizations and research centers. Check out unfamiliar groups in reliable reference tools, such as Associations Unlimited. This could mean the site is run on limited resources. While this does not always mean the site is suspect, webmasters maintaining reputable and active sites often can fix dead links in a timely fashion.
Reliable sources list the dates that revisions are made on Web pages.
The date should not be over one or two years old. The free web is a good resource, and in some ways the best resource, for very current information. Be sure to consult books, bibliographies and print indexes to journal literature, etc. Often the latest issue of a magazine is available on the Web before the library receives the print issue. The Web is a good place to find the latest discussion and public opinion on an issue.