Exam F5CAB1 Topic 1 Question 12 Discussion
Actual exam question for F5's F5CAB1 exam
Question #: 12
Topic #: 1
Question #: 12
Topic #: 1
The monitoring team reports that the SNMP server is unable to poll data from a BIG-IP device.

What information will help the BIG-IP Administrator determine whether the issue originates from the BIG-IP system?

What information will help the BIG-IP Administrator determine whether the issue originates from the BIG-IP system?
Suggested Answer: A Vote an answer
The exhibit shows aSelf IPwith:
* VLAN:Data
* Port Lockdown:Allow None
Impact of "Allow None" on SNMP
When a Self IP is configured with:
Port Lockdown: Allow None
the BIG-IP blocksallservices and ports except a few hardcoded HA communication ports.
This means:
* UDP/161 (SNMP)is blocked
* UDP/162 (SNMP traps)is blocked
* The SNMP server cannot poll or receive data from the BIG-IP through this Self IP SNMP relies on access through the Self IP if out-of-band (mgmt interface) is not used.
Thus, the issue is directly caused byPort Lockdown = Allow None, which prevents SNMP communication.
Why the other options are incorrect:
B). Traffic Group must use a floating Traffic Group
* SNMP polling doesnotrequire floating Self IPs.
* Floating groups apply to HA failover IPs, not SNMP functionality.
C). VLAN/Tunnel must allow All VLANs
* Self IPs are always bound to a VLAN; SNMP doesnotrequire All VLANs.
* As long as the Self IP belongs to a reachable VLAN, SNMP can work.
D). Configuration is correct
* It is not correct:Allow Noneblocks SNMP and is the problem.
* VLAN:Data
* Port Lockdown:Allow None
Impact of "Allow None" on SNMP
When a Self IP is configured with:
Port Lockdown: Allow None
the BIG-IP blocksallservices and ports except a few hardcoded HA communication ports.
This means:
* UDP/161 (SNMP)is blocked
* UDP/162 (SNMP traps)is blocked
* The SNMP server cannot poll or receive data from the BIG-IP through this Self IP SNMP relies on access through the Self IP if out-of-band (mgmt interface) is not used.
Thus, the issue is directly caused byPort Lockdown = Allow None, which prevents SNMP communication.
Why the other options are incorrect:
B). Traffic Group must use a floating Traffic Group
* SNMP polling doesnotrequire floating Self IPs.
* Floating groups apply to HA failover IPs, not SNMP functionality.
C). VLAN/Tunnel must allow All VLANs
* Self IPs are always bound to a VLAN; SNMP doesnotrequire All VLANs.
* As long as the Self IP belongs to a reachable VLAN, SNMP can work.
D). Configuration is correct
* It is not correct:Allow Noneblocks SNMP and is the problem.
by Montague at Dec 03, 2025, 12:03 AM
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