Latest F5 Networks F5CAB2 Practice Questions BY Shelton

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 All

Port 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 enabled

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

D . Create a Floating Self IP address

Floating 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.

4647

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.