A server administrator is bringing a new host online. After the initial OS installation and configuration, the administrator is unable to reach hosts on another subnet. The administrator is able to…

The default gateway is the Layer 3 router address that forwards packets destined for remote subnets; if it is absent or misconfigured, all traffic leaving the local subnet is dropped while local communication remains fully functional. This symptom pattern - local reachability with no cross-subnet reachability - is the textbook indicator of a default gateway misconfiguration and should always be checked first before other network parameters.

An incorrect subnet mask tends to cause communication failures within the local subnet as well, not exclusively with remote subnets, making it a less likely root cause given the described symptoms.

DNS A and AAAA records affect hostname resolution, not IP-level packet routing; the ability to ping local hosts by IP confirms Layer 3 connectivity is functional locally.

DNS reverse lookup entries map IP addresses back to hostnames for logging or identification purposes and have no effect on a host's ability to route traffic to another subnet.