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Both cloaking and geo-targeting are covered in this same chapter because they’re usually imple-
mented in practice using the same technique — IP delivery.
?
IP delivery
is the practice of using the IP, the network address of the connecting computer,
whether robot or human, and sending different content based on that. A database is used to
assist with the process. In the case of cloaking, the database stores the IP addresses of the vari-
ous spiders that may hit your site. The cloaking script implementation scans the list to see if the
current IP is a spider, and the programmer can use this information to effect changes in presen-
tation or logic. In the case of geo-targeting, the database stores various ranges of IP addresses,
and indicates where these ranges of IPs are in the world. A geo-targeting script scans the list to
see in which country the current IP is located, and the programmer can use this value to effect
changes in presentation or logic.
Usually, implementations of IP delivery cloaking also look at the
User-Agent
header of the
request. The user agent header is a header sent by both browsers and spiders. It, however,
is not regarded as authoritative, because both users and spiders may not tell the truth about
who they really are. In the former case, spiders indicate that they are humans in order to detect
spamming employing cloaking as a means to provide optimized spam content to the spiders,
while providing different content to the users. In the latter case, users (usually competitors)
may actually set the user agent in their browser to see if a site is cloaking on the basis of user
agent. It provides a convenient method for people to see if your site employs cloaking by
spoof-
ing
their user agent. This is why many implementations of cloaking do not use it as a determining
factor.
To change your user agent in your browser, see
http://johnbokma.com/mexit/2004/
04/24/changinguseragent.html
(in Firefox) or
http://winguides.com/registry/
display.php/799/
(for Internet Explorer).
More on Geo-Targeting
Geo-targeting is related to foreign search engine optimization in that it allows a site to tailor content to
various regions. For example, Google uses geo-targeting to redirect users of
www.google.com
to coun-
try-specific domains, which is a stated approval of IP delivery as an ethical practice. This is a stark con-
trast to Google’s current stated stance on cloaking.
Geo-targeting is regarded as ethical by all search engines. Matt Cutts of Google states (
http://
www.mattcutts.com/blog/boston-pubcon-2006-day-1/#comment-22227
) that “
IP delivery
[for Geo-targeting] is fine, but don’t do anything special for Googlebot. Just treat it like a typical user visiting
the site.
” However, because Google may use the actual physical location of
your web server
in the
ranking algorithms, it may be wise to use this technique to redirect your users to a server located
in their region, instead of simply changing the content. That is one example that is featured in this
chapter.
One obvious caveat with regard to geo-targeting is that it can be misled by VPNs and strange network
configurations in general that span multiple countries. This may be a concern, but it’s likely to affect a
small minority of users.
220
Chapter 11: Cloaking, Geo-Targeting, and IP Delivery
c11.qxd:c11 11:01 220


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