The Datadog Service Catalog uses a key-value syntax for searching and filtering services. To find services of a specific type, such as web services, you use the type key followed by the desired value. The query type:web correctly filters the catalog to display only the services that have been identified or tagged as web type. This is a standard, predefined facet within the Service Catalog for categorizing services based on their function (e.g., web, db, cache).

A. source is a standard attribute typically used to identify the origin of logs or metrics (e.g., nginx, redis), not the service type in the catalog.

C. version is a reserved tag used to filter services by their application version, which is essential for tracking deployments, not for filtering by service type.

D. infratype is not a standard facet key for filtering by service type in the Datadog Service Catalog. The correct key is simply type.

1. Datadog Documentation, "Service Catalog". Section: Search and Filter. The documentation lists type as a primary facet and provides type:web as an example query for filtering services.