Practice Free F5CAB2 BIG-IP Administration Data Plane Concepts (F5CAB2) exam Exam Questions Answers With Explanation

The configuration shown matches a Performance Layer 4 virtual server because it is explicitly using a FastL4 profile:

The screenshot shows Protocol: TCP and Protocol Profile (Client): fastL4.In BIG-IP data plane terms, FastL4 is the hallmark of a Performance (Layer 4) virtual server, designed to process connections at Layer 4 with minimal overhead (high throughput/low latency) compared to full proxy L7 processing.

The screenshot also shows HTTP Profile (Client): None (and HTTP server profile effectively not in use).A Standard virtual server commonly uses full-proxy features and frequently includes L7 profiles (like HTTP) when doing HTTP-aware load balancing, header manipulation, cookie persistence, etc. In contrast, a Performance L4 virtual server typically does not use an HTTP profile because it is not doing HTTP-aware (Layer 7) processing.

It is not a Forwarding IP virtual server:A Forwarding (IP) virtual server is used to route/forward packets (often without load balancing to pool members in the same way as Standard/Performance VS) and is selected by choosing a forwarding type. The presence of a TCP protocol with a FastL4 client profile aligns with a Layer 4 load-balancing style virtual server, not a packet-forwarding virtual server type.

Conclusion: Because the configuration is TCP-based and explicitly uses fastL4 with no HTTP profile, the expected BIG-IP virtual server type is Performance Layer 4 (Option C).

In BIG-IP traffic management, persistence profiles cause existing client connections (and subsequent requests) to be repeatedly sent to the same pool member. When persistence is enabled, simply preventing new connections is not sufficient if the requirement is to immediately remove all existing connections.

Key behavior of pool member states:

Forced Offline

Immediately removes the pool member from load balancing.

Terminates all existing connections, regardless of persistence.

Prevents new connections from being established.

This is the correct state when urgent maintenance or troubleshooting is required.

Disabled

Prevents new connections from being sent to the pool member.

Allows existing connections to continue, which is not acceptable when persistence is configured and connections must be cleared immediately.

Offline (non-forced)

Similar to Disabled behavior depending on context.

Does not guarantee immediate termination of existing connections.

Manually deleting connections via the command line

Is unnecessary and operationally inefficient.

BIG-IP already provides a supported mechanism (Forced Offline) to cleanly and immediately remove traffic.

Conclusion:

To immediately remove all existing connections, including those maintained by persistence, the BIG-IP Administrator must set the pool member to a Forced Offline state. This directly satisfies the requirement without additional manual steps.

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Virtual Servers have a setting called VLAN and Tunnel Traffic which defines where the BIG-IP "listens" for new connections.4849

Ingress Logic: A virtual server is an entry point. It must be enab50led on the VLAN where the Client resides. If a client is on the "51Internal" VLAN, the Virtual Server must be enabled there to receive the traffic.

Egress Logic: The BIG-IP system uses the TMM Routing Table and Self-IPs to reach pool members. It does not need the Virtual Server to be "enabled" on the destination VLAN (External) to send traffic there.

Default Behavior: By default, Virtual Servers are enabled on "All VLANs." However, if restricted for security, the administrator must ensure the Virtual Server is active on the client-facing (ingress) VLAN.

In a BIG-IP high availability (HA) configuration, Auto-Sync is a device trust feature that automatically synchronizes configuration changes from the Active device to the Standby device within a Sync-Failover device group.

Key principles from BIG-IP Administration Data Plane Concepts:

The Active device is always the authoritative source of configuration

Configuration changes are intended to be made only on the Active device

With Auto-Sync enabled, any time the Active device configuration changes, the system automatically pushes the configuration to all Standby members of the device group

Configuration changes made directly on a Standby device are not preserved

In this scenario:

The administrator modifies a Virtual Server on the Standby device

That change is local only and does not alter the device group’s synchronized configuration

When Auto-Sync next runs (triggered by a change on the Active device or an internal sync event), the Active device configuration overwrites the Standby configuration

As a result, the configuration change made on the Standby device is undone.

Why the Other Options Are Incorrect:

A – The change is not undone only when another change is made; it is undone during the next Auto-Sync operation

B – Changes made on the Standby device are never propagated to the Active device

D – Auto-Sync does not merge or promote Standby changes into the HA pair configuration

Best Practice Reinforced:

Always perform configuration changes on the Active BIG-IP device when Auto-Sync is enabled to ensure consistent and predictable HA behavior.

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Redundant BIG-IP systems (HA pairs) must maintain constant communication to monitor the health of the peer and synchr15onize states.16

Heartbeats: By default, even with a serial cable, th17e BIG-IP systems exchange "heartbeat" packets over the network to determine if the peer is still alive.

Network Failover: This involves the exchange of UDP packets (typically on port 1026) at regular intervals.

Device Service Clustering (DSC): Modern BIG-IP versions use the Central Management (cm) infrastructure to communicate configuration status and sync status constantly.

Clarification on others: Port lockdown does affect HA communication if misconfigured (A is false). Mirroring uses separate channels (B is false). Mirroring is never sent over the serial cable because it requires high bandwidth (D is false).

For BIG-IP to send or receive traffic on a VLAN, that VLAN must be bound to a physical interface or a trunk. Creating a VLAN object and a Self IP alone is not sufficient to 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 a Layer 2 connectivity issue, not a Layer 3 or HA issue.

Why assigning a physical interface fixes the problem:

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

A physical interface (e.g., 1.1), or

A trunk

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 accessed on 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 has no physical interface assigned. To restore connectivity, the BIG-IP Administrator must assign a physical interface (or trunk) to the VLAN, enabling Layer 2 traffic flow.