A control component of a computing environment initiates sending of request(s) over a network of the computing environment by an activated virtual adapter. The activated virtual adapter is hosted on a physical adapter of a host system coupled to the network, and is for use by a guest, hosted by the host system, in performing data input and output. The request(s) retrieve access control information from the network indicative of access control(s) enforced in controlling access by the activated virtual adapter to network component(s). The initiating provides indication(s) to the physical adapter, absent involvement of the guest, that the request(s) be sent by the virtual adapter. Based on the initiating, the control component obtains the access control information from the physical adapter, and determines, based on that information, the access control(s) being enforced by the network in controlling access by the activated virtual adapter to the network component(s).