1D0-61C · Question #60
Network upgrades have been completed and the WINS server was shutdown. It was decided that NetBIOS network traffic will no longer be permitted. Which of the following will accomplish this objective?
The correct answer is B. Port filtering. Port filtering is correct because NetBIOS operates on specific, well-known ports - UDP/TCP 137 (Name Service), UDP 138 (Datagram Service), and TCP 139 (Session Service). Blocking these ports at a firewall or router effectively prevents NetBIOS traffic from traversing the…
Question
Network upgrades have been completed and the WINS server was shutdown. It was decided that NetBIOS network traffic will no longer be permitted. Which of the following will accomplish this objective?
Options
- AContent filtering
- BPort filtering
- CMAC filtering
- DIP filtering
How the community answered
(55 responses)- A5% (3)
- B82% (45)
- C2% (1)
- D11% (6)
Explanation
Port filtering is correct because NetBIOS operates on specific, well-known ports - UDP/TCP 137 (Name Service), UDP 138 (Datagram Service), and TCP 139 (Session Service). Blocking these ports at a firewall or router effectively prevents NetBIOS traffic from traversing the network regardless of source or destination.
Content filtering (A) inspects the payload or URLs of traffic (e.g., blocking adult websites), not the underlying protocol or port - it has no mechanism to suppress a specific network service like NetBIOS. MAC filtering (C) controls which physical devices can connect to a network segment based on hardware addresses, but does nothing to restrict what type of traffic those devices can send. IP filtering (D) blocks traffic based on source or destination IP addresses; since NetBIOS can run between any two IPs, blocking IPs would require blocking all internal hosts rather than targeting the protocol itself.
Memory tip: Think "protocol = port." When a question asks you to stop a specific service or protocol (NetBIOS, FTP, Telnet), the answer is almost always port filtering - each service has a signature port number that acts as its address on a machine.
Topics
Community Discussion
6
Dervla O.Dec 10, 2025Port filtering is the right call here. NetBIOS runs on specific, well-known ports, primarily 137, 138, and 139, so blocking those at the firewall or router level is a precise, surgical way to stop that traffic cold. Content filtering looks at what is inside packets, MAC filtering controls access by hardware address, and IP filtering targets source or destination addresses, none of which directly targets the protocol itself. When the goal is to kill a specific protocol across the network, you block the ports it depends on, full stop.
Samuel O.Dec 28, 2025Saw this one and immediately thought of our old NetBIOS cleanup project, port 137 gone, B all day.
Ingrid P.Dec 19, 2025Port filtering is the right call here, since NetBIOS rides on well-known ports (137, 138, 139) and blocking those at the firewall drops the traffic cleanly. IP filtering is the tempting distractor because people conflate "blocking traffic" with "blocking addresses," but IP filtering targets source or destination addresses, not protocols or services, so it would not reliably stop NetBIOS on its own.
Dervla O.Dec 21, 2025Port filtering is the stronger primary control here, agreed, but pairing it with IP filtering at the perimeter is worth the extra step since unmanaged or rogue devices can still originate NetBIOS traffic from unexpected internal addresses.
Mei-Ling H.Jan 7, 2026MAC filtering blocks specific devices, stopping NetBIOS traffic at its source.
Dervla O.Jan 9, 2026MAC filtering controls device access by hardware address, not by protocol or traffic type, so it would not stop NetBIOS specifically. Option B is correct because NetBIOS traffic operates on specific ports and protocols that a firewall or protocol filter can target directly.