A user reports that an internal application server, app.corp.local, is unreachable from a Linux workstation, while other internal hosts work fine. From the workstation, 'ping app.corp.local' returns 'Name or service not known', but 'ping 10.20.5.42' (the server's IP) succeeds. Running 'dig app.corp.local' against the configured DNS server returns NXDOMAIN. Other administrators confirm the DNS record exists and resolves correctly from their machines. What is the MOST likely cause on this workstation?