Howie Jacobson, author of AdWords for Dummies, asked me about the SEO implications of aliasing multiple domain names to one IP address as a workaround for Google's new AdWords rule change. As of April 1st, Google no longer allows a display URL in your Google ad if it redirects to a different domain name.

This rule change is unfortunate, as it restricts search marketers' ability to A/B test different domain names in their Google ads. So if you wanted to test www.widgetshelp.com versus your main URL of www.widgetsllc.com, you'd need to remove the redirect from www.widgetshelp.com. Thus you'd have a CNAME or A record in your DNS server for widgetshelp.com, and you'd have a "ServerAlias www.widgetshelp.com widgetshelp.com" line in your Apache config.

But without a redirect, search engine spiders won't know which URL is the canonical one. Widgetshelp.com and widgetsllc.com would look like duplicates of each other, and the link juice to each URL would be split up rather than aggregated together. This becomes an issue when there are links to the alternate domain, as the spiders will find that duplicate site. By the way, don't worry about spiders following the link in the Google ad, as that is not a spiderable link.

Unfortunately the "Preferred Domain" tool in Google Webmaster Central is not going to be a help here, because it only lets you select between www vs. non-www. You can't specify multiple domain names -- at least not yet. Back in 2006 I recommended to Google that they Extend their canonicalization feature in Webmaster Central. Even though they haven't heeded my request, I'm still hopeful that they someday will.

In the meantime, there's a gray hat solution you could implement -- a conditional redirect that only spiders see. It's not without risks, however. You have been warned.

Alternatively, you could contact the site owners who have linked to your alternate domains and ask them to update the link to your main URL. That can only really work if you only have just a few links pointing to your alternate domain. And obviously, don't link to your alternate domain yourself!

Late last month I spoke at the "Successful Online Advertising conference in Auckland. One of the questions that came up during the session on paid search was around the tactics of gap surfing and bid jamming. A lot of people in the audience didn't know the definitions of these terms; in fact, many had not even heard of them before. I'd guess that many of my readers are similarly unfamiliar with these two concepts. So I thought it might be useful to define them.

First off, bid jamming is something you can do in Yahoo! Search Marketing (formerly known as Overture). Bid jamming is when you increasingly raise your bid amount to just a penny below the top bidder who has foolishly set their maximum bid amount way too high. This forces the top bidder to pay that max bid amount per click, whereas you only have to pay one penny more than the bidder underneath you. Of course, this can cost the competitor a lot of money quite quickly but, if you are not careful, you can get bid jammed yourself in the process.

Gap surfing is a tactic for ensuring your bid is no more than it needs to be to maintain your target rank. So if you are happy to be lower than #1 position and you don't want to pay too much, you might want to use this tactic. In a nutshell, you scan through the top ranking ads and find the big gaps in bid prices and you bid at the bottom of one of those gaps -- e.g. the biggest gap within the top five positions.

I would recommend staying clear of bid jamming, and I would employ gap surfing only if you have a bid management tool that supports this capability. I wouldn't try and accomplish it manually. Particularly since Google AdWords doesn't even show you everyone's bid amounts, so you'd have to continually revise your own bid amounts and monitor your position until you figured out the gaps.

As you can see, there is a lot of complexity and subtleties in pay-per-click (PPC) search advertising, and we're only scratching the surface here. It goes on to include sophisticated web analytics, and constant automated revisions of bid amounts based on the web analytics data (e.g. the technique of dayparting). Trying to manage pay per click campaigns without the proper tools is like showing up at a gunfight with a sword. ;-)