Why 301 to external site instead of direct link

[aakk9999]

I am not sure if this is the right forum, so feel free to move the post if it is not.

There is an external site that shows the banner of our site. When banner is clicked on, the visitors are sent to our site, but this is done via 301 redirect rather than having a direct link.

Why would this be done this way? Is there any SEO advantage to the external site to have their internal link under banner and when clicked, internal link does 301 to us?

Also, is there any SEO disadvantage to our site for this to be done in such way?

I know of 302 hijack, but this is definitely 301 redirect, not 302, we checked up in fiddler.

[rainborick]

Some sites do this to track clicks, and some might do it as a part of managing their link exchanges. The actual link points to a script that can record the user click and then redirects the user (or search engine) to the destination URL. There's no SEO advantage to the originating site since the 301 ostensibly redirects the link value to the destination.

[Shaddows]

When we've done such advertising campaigns in the past, the link value was marginal anyway. We use banners strictly for direct traffic.

[steveb]

One redirect will pass link power. Two won't.

It's common to do this to count click on the link.

[wildbest]

You'd better take care if there is straight 301 or there are redirect chains. Redirect chains can kill your site with some search engines. They are best avoided. If you have something like redirect 301 > 302 > 302 > 200 some SEs can cache an empty site (the second 302) instead of yours (the fourth 200). It happened to one of our sites recently and Yahoo cache for this website was showing an empty page!

[aakk9999]

Thank you very much for replies.
Clicking on banner when Fiddler is running shows straight 301, unless something can be hidden from fiddler
I have no problem with leaving link being 301 if it only counts clicks on their site as neither we are paying for a banner nor it was a link exchange.