Skynet is rarely depicted visually in any of the Terminator media. Skynet gained self-awareness after it had spread into millions of computer servers all across the world; realizing the extent of its abilities, its creators tried to deactivate it. In the interest of self-preservation, Skynet concluded that all of humanity would attempt to destroy it and impede its capability in safeguarding the world. Its operations are almost exclusively performed by servers, mobile devices, drones, military satellites, war-machines, androids and cyborgs (usually a terminator), and other computer systems.
This skill assumes that Alexa has is in communication with Skynet and able to ask her to list a random friend of hers from a list of over 500+ computers that have appeared in notable works of fiction.