What are ports 161 and 162 used for?
Ports 161 and 162 are SNMP, the protocol monitoring systems use to watch switches, routers, printers, servers and UPS units. The management station polls each device's agent on 161; devices send unsolicited alerts, called traps, to the manager on 162.
A poll asks for values such as interface traffic, CPU load or toner level, each identified by an object ID defined in a MIB. A trap is the device speaking first, for example when a link goes down or a power supply fails. Versions 1 and 2c protect access only with a community string sent in clear text. A community string left at a guessable default gives anyone who can reach port 161 a map of the network or, with write access, control of the device.
Are ports 161 and 162 TCP or UDP?
UDP. Queries go to the agent on UDP 161 and notifications go to the manager on UDP 162.
Is SNMP on ports 161 and 162 secure?
Only version 3 is. SNMPv3 adds per-user authentication and encryption. SNMPv1 and v2c send the community string in clear text, so the hardening steps are: use v3, remove default community strings and allow port 161 only from the monitoring server.
Port 161 vs port 162: what is the difference?
Who starts the conversation. On 161 the manager asks and the device's agent answers. On 162 the device sends a trap to the manager without being asked. Monitoring needs 161 open towards the devices and 162 open towards the manager.
Which CompTIA exams list ports 161 and 162?
CompTIA lists ports 161 and 162 by number in the Network+ objectives; the A+ Core 1 port list does not include them.
- Network+ N10-009: objective 1.4 (Networking Concepts), listed as “Simple Network Management Protocol (SNMP), 161/162”.
The quoted text is how the objectives document lists the port. The exam puts the port in a scenario, such as a firewall rule or a failed connection; it does not only ask for the number.
Check yourself: a practice question
Written by CertSprint for this page. It is not taken from any exam.
A monitoring server can poll a switch for interface counters, but never receives the switch's link-down alerts. Which port is most likely blocked between the switch and the server?
- UDP 162
- UDP 161
- TCP 22
- TCP 443
Show the answer
A. UDP 162. Polling uses 161 and is working. Traps travel from the device to the manager on UDP 162.
Sources: IANA Service Name and Transport Protocol Port Number Registry: port 161; RFC 3417: Transport Mappings for the Simple Network Management Protocol (SNMP); RFC 3414: User-based Security Model (USM) for version 3 of SNMP. The port number and how each exam lists it come from CompTIA's exam objectives, linked from the study plans above. The explanation and the question are CertSprint's own, checked against these sources on 12 November 2026.