Track online traffic for your websites subdomains

It is recommend to use a single Google Analytics 4 (GA4) property with one data stream for all subdomains.

Out of the box, GA4 can tracks across all subdomains within a single property as long as they share the same Measurement ID. Users moving between subdomains will retain the same GA4 Client ID, preventing session breaks so it imperative that you set up cross-domain tracking.

GA4's features, such as custom dimensions and segments, allow you to effectively analyze subdomain data within a single data stream. Use custom dimensions (Page Location) to track the subdomain as a parameter. Use segments to filter and analyze data for specific subdomains. This way you can have the best of both worlds, a single data stream, and the ability to isolate and analyze individual subdomain performance.

In the above example, I use the 'Page Location' dimension in an exploration report to segment the website traffic based on sub-domains.

A single data stream offers the following benefits :

• Simplified setup and management.

• Consolidated data for a holistic view of your website.

• Easier cross-subdomain user journey analysis.

• Simplified reporting, as you're working with a single data set.

In addition, with a single data stream in GA4, this also avoids the complication of separately setting up and manage Audiences, custom dimensions & metrics, events, and conversions.