What does ARP do, and why does it not find a remote server’s MAC address across the internet?

ARP resolves an IPv4 next-hop address to a link-layer address on the local network. If a destination is outside the local subnet, the host ordinarily resolves the local gateway’s address rather than the remote server’s MAC address. Routers replace link-layer framing at each hop. Inspect subnet configuration, routing, and the neighbor cache when investigating local delivery failures. ARP has no built-in authentication and can be abused on a local network, so appropriate network protections matter. IPv6 uses Neighbor Discovery rather than ARP.