F5-CA F5CAB2 Updated Exam

Comprehensive and Detailed Explanation (BIG-IP Administration – Data Plane Concepts):

On BIG-IP systems,physical interface bandwidth is fixedby the link speed (for example, 1GbE or 10GbE). When traffic demand exceeds the capacity of a single interface, BIG-IP provideslink aggregationthroughtrunks.

Key concepts involved:

InterfacesA single physical interface (such as 1.1) is limited to its negotiated link speed. You cannot exceed this capacity through software tuning alone.

Trunks (Link Aggregation)Atrunkcombines multiple physical interfaces into a single logical interface.

BIG-IP supports LACP and static trunks.

Traffic is distributed across member interfaces, increasingaggregate bandwidthand providingredundancy.

VLANs are then assigned to thetrunk, not directly to individual interfaces.

Why optionBis correct:

Creating atrunk with two interfacesallows BIG-IP to use both physical links simultaneously.

This increases total available bandwidth (for example, two 10Gb interfaces → up to 20Gb aggregate capacity).

This is thedocumented and supported methodfor scaling bandwidth on BIG-IP.

Why the other options are incorrect:

A. Increase the MTUMTU changes affect packet size and efficiency,not total bandwidth capacity.

C. Assign two interfaces to the VLANBIG-IP doesnotsupport assigning a VLAN to multiple interfaces directly. VLANs must be associated withone interface or one trunk.

D. Set the media speed manuallyMedia speed can only be set up to the physical capability of the interface and connected switch port. It cannot exceed the hardware limit.

Conclusion:

To increase total available bandwidth on BIG-IP when a single interface is insufficient, the administrator must create atrunk object with multiple interfacesand move the VLAN onto the trunk. This aligns directly with BIG-IP data plane design and best practices.

Comprehensive and Detailed Explanation (BIG-IP Administration – Data Plane Concepts):

For BIG-IP to send or receive traffic on a VLAN, that VLANmust be bound to a physical interface or a trunk. Creating a VLAN object and a Self IP alone isnot sufficientto establish data-plane connectivity.

From the exhibit:

The VLAN (vlan_1033) exists and has a tag defined.

A Self IP is configured and associated with the VLAN.

However, traffic cannot reach servers on that VLAN.

This indicates aLayer 2 connectivity issue, not a Layer 3 or HA issue.

Whyassigning a physical interfacefixes the problem:

BIG-IP VLANs do not carry traffic unless they are explicitly attached to:

Aphysical interface(e.g., 1.1), or

Atrunk

Without an interface assignment, the VLAN is effectively isolated and cannot transmit or receive frames, making servers unreachable regardless of correct IP addressing.

Why the other options are incorrect:

A. Set Port Lockdown to Allow AllPort Lockdown controls which services can be accessedon the Self IP(management-plane access), not whether BIG-IP can reach servers on that VLAN.

B. Change Auto Last Hop to enabledAuto Last Hop affects return traffic routing for asymmetric paths. It does not fix missing Layer 2 connectivity.

D. Create a Floating Self IP addressFloating Self IPs are used for HA failover. They do not resolve reachability issues on a single device when the VLAN itself is not connected to an interface.

Conclusion:

The servers are unreachable because the VLAN hasno physical interface assigned. To restore connectivity, the BIG-IP Administrator mustassign a physical interface (or trunk) to the VLAN, enabling Layer 2 traffic flow.

Comprehensive and Detailed Explanation From BIG-IP Administration Data Plane Concepts documents:

In BIG-IP LTM, apool member statedirectly affects how traffic is handled at the data plane level. When a pool member ismanually disabled, BIG-IP changes the member’s availability state todisabled, which has specific and predictable traffic-handling consequences.

According to BIG-IP Administration Data Plane Concepts:

Adisabled pool member:

Doesnot accept new connections

Continues to processexisting non-persistent connectionsuntil they naturally close

Isremoved from load-balancing decisions, including persistence lookups

Most importantly for this question:

Persistent connections(such as those created using source-address persistence, cookie persistence, or SSL persistence) arenot honoredfor a disabled pool member

BIG-IP willnot send new persistent trafficto a disabled member, even if persistence records exist

Therefore, when a pool member is manually disabled, itstops processing persistent connections, while allowing existing non-persistent flows to drain gracefully.

Why the Other Options Are Incorrect:

B– Persistent connections are not honored for a disabled pool member

C– Existing connections are not immediately terminated when a pool member is disabled

D– Only the disabled pool member stops accepting new connections, not all pool members

Key Data Plane Concept Reinforced:

Manually disabling a pool member is agraceful administrative actionthat prevents new and persistent traffic from reaching the member while allowing existing connections to complete, which is critical for maintenance and troubleshooting scenarios.

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