SNMP Flashcards
Simple Network Monitoring Protocol
T/F: SNMP can be used to make configuration changes
T
What are the two main types of devices in SNMP
1) Managed Devices (switches, routers)
2) Network Management Stations (NMS)
What are the 3 main functionalities provided by SNMP
1) Managed devices notify NMS of events (failures, restoration, etc)
2) NMS can ask managed devices for their status
3) NMS instructs managed devices to make a config change
What are the two components of the NMS’s SNMP software
1) SNMP Manager, interacts with managed devices
2) SNMP Application, provides UI for admins
What is the function of an NMS’s SNMP Manager component
To interact with managed devices. Receives notifications, sends requests for information, sends config changes, etc.
What is the function of an NMS’s SNMP Application component
To provide a UI for a sysadmin to interact with. Displays alters, statistics, charts, etc
What are the two components of a Managed Device’s SNMP software
1) SNMP Agent
2) Management Information Base (MIB)
What is the function of a Managed Device’s SNMP Agent
To interact with the SNMP manager on the NMS. Send notifications, receive config change orders, etc.
What is a Managed Device’s Management Information Base (MIB)
The structure that contains the variables that are managed/reported by SNMP
T/F: each variable in the MIB is identified by an Object ID (OID)
True
How are SNMP OIDs organized
A hierarchical structure.
Essentially works by organizing variables in sub directories, and each number represents a level.
For example -> 1.3.6.1.2.1.1.5 ::
– iso
– identified-organization
– dod
– internet
– mgmt
– mib-2
– system
– sysName
This variable would give you the hostname for a cisco device, if a NMS requested this OID
What are the 3 major versions of SNMP that achieved widespread use
v1
v2c
v3
What is the version of SNMP widely in use today
v3
What are the classes of SNMP messages
Read
Write
Notification
Response
What is the well known listening port for an SNMP trap
UDP 162
What does a Cisco device use to respond to GET requests
SNMP agent
What is a benefit of using SNMPv3 instead of v2
Encryption and authentication between devices
What is the benefit of using the correct MIB with a Cisco router
Ensures you have correct SNMP operations. Each different device can have different MIBs, so you have to configure your SNMP manager to read correctly
What is the well known listening port for SNMP agents
UDP 161
What type of SNMP request is used by the manager to configure an SNMP managed device
Set
What are the sub-types of the SNMP read message class
Get
GetNext
GetBulk
Explain the difference between the Get, GetNext, and GetBulk read message types
“Get” retrieves the value of one or more OIDs. Agent will send a Response message with current value for each variable
“GetNext” requests available variables in the managed device’s MIB
“GetBulk” is a more efficient version of the GetNext message, was introduced in SNMPv2
What are the sub-types of the SNMP write message class
There is only 1:
Set
Explain what the Set write message type does
Request sent from manager to an agent to change the value of one or more variables. Agent will send a Response class message with the new values
What are the sub-types of the SNMP notification message class
Trap
Inform
Explain what the Trap message type does
A notification sent from the agent to the manager. The manager doesn’t send a Response message to acknowledge it received the Trap, so this is considered an unreliable message
Explain what the Inform message type does
A notification that is acknowledged with a Response message. Can be sent/received by either the manager or the managed device
What are the sub-types of the SNMP response message class
Just one, response
Explain what the Response message type does
Message sent in response to a previous message/request, essentially an acknowledgement message
Does SNMP use TCP or UDP for communications?
UDP
