Which NBNS query type is commonly sent to discover names within a local network?

• A. MX query
• B. PTR query
• C. A record query
• D. Name query broadcast

Answer: (D)

NetBIOS name resolution on a local network often uses a Name Query that is broadcast to the local subnet. When a device needs to map a NetBIOS name to an IP and there isn’t a known WINS server or a cached entry, it sends a Name Query asking “Who has this NetBIOS name?” to the broadcast address on UDP port 137. Any host that owns that NetBIOS name can respond with its IP, allowing the requester to establish communication. This broadcast discovery is specific to NBNS and is commonly used for local-name resolution without prior knowledge of the target host.

The other options are DNS-related queries and do not pertain to NBNS name discovery. An MX query asks for mail server information, a PTR query is for reverse DNS lookups, and an A record query retrieves an IPv4 address for a domain—none of these are used for discovering NetBIOS names on the local network.