Spam in blogs or comment spam are known as one of the most widely used forms of spamdexing in SEO or search engine optimization. This technique involves the use of blogs in which a spammer would manually or automatically post comments with their links in it. Other than blogs, wikis, guestbooks, or any other web application that accepts and displays hyperlinks submitted by visitors may be a target.
Because of the severity of this technique to manipulate the SERPs (search engine result pages), as well as to prevent flooding, many of today's blog sites have implemented several solutions to deal with this matter. Some of these solutions are improvised by bloggers while some were introduced by search engines to prevent this type of spamdexing to take any effect. These solutions include:
IP Blocking
Spammers would usually reply on their own comment. Checking that the user's IP address is not replying to a user of the same IP address will significantly reduce flooding. According to several SEO Philippines consultants, this however proves problematic in the fairly rare instance when multiple users, behind the same proxy, wish to comment on the same entry.
Disallowing links
Many of today's blog, and other web applications, are known to block the use of links within comments or posts. This however would create problems if the spammer uses an automatic blog spamming software. While this is highly effective, spammers do frequently send gibberish posts (such as "ajliabisadf ljibia aeriqoj") to test the spam filter. These gibberish posts will not be labeled as spam. They do the spammer no good, but they still clog up comments sections.
Redirects
Instead of displaying a direct hyperlink submitted by a visitor, a web application could display a link to a script on its own website that redirects to the correct URL. According to SEO Philippines experts, this will not prevent all spam since spammers do not always check for link redirection, but effectively prevents against increasing their PageRank, just as relnofollow.
NoFollow tag
The use of the relnofollow tag have been one of the few successful solutions to addressing blog spams. Google announced in early 2005 that hyperlinks with rel"nofollow" attribute would not be crawled or influence the link target's ranking in the search engine's index. The Yahoo and MSN search engines also respect this tag.
The use of AJAX
Some blog software such as Typo allow the blog administrator to allow only comments submitted via Ajax XMLHttpRequests, and discard regular form POST requests. According to many SEO Philippines experts, this causes accessibility problems typical to Ajax-only applications.
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