Your Questions Answered: Tracking sources across domains


A recent question in the blog questions box (at the right, and please suggest questions if you have them):

My funnel goes something like this:

  1. A visitor clicks on an AdWords ad and lands on SiteA with the ?gclid tracking parameter
  2. The visitor clicks through to SiteB (which I control as well) and makes purchase

On SiteA, I’ve set up links so that the full query string is passed from page to page as the visitor clicks around. If the visitor lands on, each page they visit will have that query string ?gclid=12345. When they click through to SiteB, I can see that they came to SiteA (referrer) from Google (w/ ?gclid=). Does having the ?gclid parameter on all URLs on SiteA do anything to reports in either Adwords or Analytics for SiteA?

There are really 2 issues here: First, what does the gclid parameter do? Second, when we have a visit that starts on one site and converts on another, what’s the best way to see how someone arrived (on SiteA) and whether they converted (on SiteB)?

AdWords tracking

The gclid parameter, all by itself, just gives you a numeric identifier that you can’t do much with. However, it enables Google to do all kinds of magic behind the scenes by letting you access a whole suite of AdWords reports.

So if you’re just seeing the gclid parameter in your URLs in Google Analytics, you’re missing out on a whole ton of data about AdWords. How do you fix it? See this post on troubleshooting the link between your AdWords and Analytics accounts (an oldie but a goodie). Get that set up right, and suddenly you have all kinds of information about individual campaigns, keywords, placements, and ads — including things you can’t get in AdWords, like Bounce Rates and even an ROI calculation (if you have goal values or ecommerce revenue data to calculate it from)!

Landings on one site, Conversions on another

Believe it or not, this is a common problem. Lots of sites have a separate web application for a shopping cart (or donation site, or member signup site, etc.). People land on your “main” site (SiteA) but you send them to the other site (SiteB) to actually fill out some forms and convert.

Sure, by default you can see SiteA as a referrer (in the Referring Sites report) for the data for SiteB. But this isn’t ideal, because what we really want to know is, how did this visitor arrive at SiteA, and did they convert on SiteB? Basically, we want to treat them as one big site, even though they are actually two separate domains.

Google Analytics lets you do this through a feature called cross-domain tracking. It involves making changes to your tracking code on both sites to track them together and follow a visit across both sites, passing the information about the visit from SiteA to SiteB when the visitor crosses over. For more information, you can look in the Help Center, in the developer documentation on Google Code, or check out a book like Advanced Web Metrics with Google Analytics, which has a section in Chapter 7 about cross-domain tracking.

Jonathan Weber is our Data Evangelist, focusing on bringing the strategic value of data analysis to our customers. He spreads the principles of analytics through our training seminars and even wrote a book on Google Analytics & Tag Manager. Before he caught the analytics bug, he worked in information architecture. Away from the computer, you can find him as a flower farmer and plant geek.

  • Mary Kay Lofurno

    We are testing cross domain tracking on some dummy sites we set up before we roll it out to our sites.

    My question is this…how do you use the goals and funnels when one goal url is on one site and the first step of the funnel is on another site entirely. For the steps of the funnel, you cannot put in whole urls and it assumes that everything step is the same as the goal url..any help is greatly appreciated.

    Thanks, Mary Kay

  • Mary Kay Lofurno

    So it looks something like…

    step (1)
    step (2)
    step (3)
    step (4) (goal url)

  • Cross-domain got me stuck for a while. I was expecting under “content” for the “landing page” to show different domains. currently it only shows the various sub-domains.

  • Jonathan

    Mary Kay — by default in GA, the URL just contains the /funnel1 part, the path of the URL, and not the hostname. Generally, you want to use a filter on your profile to add the hostname onto the URL so you can specify that in your funnel setup as well. That’s described here: where it says “Modify your cross-domain profile with a filter to show the full domain in your content reports”.

    Windfery — When you do cross-domain tracking, you are treating the sites as one big site, and a visitor has a single session across all of those sites. The landing page for their visit is the very first page they saw on any of those sites during that visit. So you should see landing pages of the first pages those visitors saw on those domains, but you won’t see a landing page when a visitor goes from domain A to domain B.

Contact Us.

Follow Us



We'll get back to you
in ONE business day.
Our Locations
THE FOUNDRY [map] LunaMetrics

24 S. 18th Street
Suite 100

Pittsburgh, PA 15203


4115 N. Ravenswood
Suite 101
Chicago, IL 60613


2100 Manchester Rd.
Building C, Suite 1750
Wheaton, IL 60187