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Affiliate Pages

Imagine that you have a product, The Ultimate Widget. You set up a great web affiliate program that

pays 50% of revenue on the product, and everyone wants to join. Soon, you have thousands of affiliates

applying. To indicate to your application which affiliate it was, you add a parameter

?aff=<aff_id>

.

In this scenario, your main page for The Ultimate Widget would be located at an URL such as this:

http://www.example.com/Products/The-Ultimate-Widget/

Your associates would sell the exact same product, which has (naturally) the same product details,

through links like these:

http://www.example.com/Products/The-Ultimate-Widget/?aff=123

http://www.example.com/Products/The-Ultimate-Widget/?aff=456

Unfortunately, assuming all these links were spidered, you now have thousands of pages of duplicate

content. This can be a profound problem. As mentioned in the introduction to this chapter, in the worst

case, excessive duplicate content can get a site penalized. Special care must be taken to mitigate this

problem. Fortunately, there are a few fairly easy solutions.

Using Referrers and Cookies instead of Query String Parameters

Using referrers is effective in that it completely transparently informs your application of where the traffic

comes from; simply match the

$_SERVER[

‘

HTTP_REFERER

‘

]

variable against a domain name (or a com-

plete URL if desired), and if there is a match, set a session variable or a cookie accordingly.

One major caveat of this method is that certain security software deliberately masks the content of

HTTP_

REFERER

, and thus a small amount of affiliate traffic will be unaccounted for. Whether this is acceptable

is between you and your affiliates. The obvious upside is that all links are entirely without parameters,

and to a search engine it looks like a natural link, not an affiliate link. This is potentially great for a link-

building campaign.

Such a system also presents more maintenance if a particular affiliate wants to promote your product on

more than one site, and by the same token such links could not be used effectively on public forums such

as bulletin boards and blog comments.

This method is not demonstrated here because it is typically not a viable solution.

Using Excluded Affiliate URLs

You can also use

robots.txt

or meta-exclusion, as previously discussed, to exclude all URLs that are

associated with the affiliate program. For example, you could add the following tag to every affiliate page:

<meta name=”robots” content=”noindex, nofollow”>

Alternatively, you could place the affiliate script in a subdirectory and exclude it in

robots.txt

:

User-agent: *

Disallow: /aff/

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Chapter 5: Duplicate Content

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