F5 F5CAB2 Dumps

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

In BIG-IP high availability (HA) configurations, MAC Masquerade is used to speed up failover by allowing traffic-group-associated Self IPs to retain the same MAC address when moving between devices. This prevents upstream switches and routers from having to relearn ARP entries during a failover event, resulting in near-instant traffic recovery.

By default, MAC masquerade applies one MAC address per traffic group, regardless of how many VLANs the traffic group spans. This can create problems in some network designs because the same MAC address appearing on multiple VLANs may violate network policies or confuse switching infrastructure.

To address this, BIG-IP provides Per-VLAN MAC Masquerade, enabled by the database variable:

`tm.macmasqaddr_per_vlan = true`

When this feature is enabled:

BIG-IP derives a unique MAC address per VLAN

The base MAC address configured on the traffic group remains the first four octets

The last two octets are replaced with the VLAN ID expressed in hexadecimal

The VLAN ID is encoded in network byte order (high byte first, low byte second)

### VLAN ID Conversion:

VLAN ID: 1501 (decimal)

Convert to hexadecimal:

1501₁₀ = 0x05DD

High byte: 05

Low byte: DD

### Resulting MAC Address:

Base MAC: `02:12:34:56:00:00`

Per-VLAN substitution → last two bytes = `05:DD`

Final MAC address:

`02:12:34:56:05:dd`

### Why the Other Options Are Incorrect:

A (01:15) – Incorrect hexadecimal conversion of 1501

B (dd:05) – Byte order reversed (little-endian, not used by BIG-IP)

D (15:01) – Uses decimal values instead of hexadecimal

### Key BIG-IP HA Concept Reinforced:

Per-VLAN MAC Masquerade ensures Layer 2 uniqueness per VLAN while preserving the fast failover benefits of traffic groups, making it the recommended best practice in multi-VLAN HA deployments.

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

To select the correct virtual server type, an administrator must balance the need for L7 intelligence versus raw throughput and hardware offloading:

Performance (Layer 4) Virtual Server:This type is designed for maximum speed. It uses thefastL4profile, which allows the BIG-IP system to leverage theePVA (Embedded Packet Velocity Accelerator)hardware chip. When a Performance (L4) virtual server is used, the system processes packets at the network layer (L4) without looking into the application payload (L7). This fulfills the requirement for hardware acceleration and avoids the overhead of HTTP optimization features, which are not needed in this scenario.

Performance (HTTP) Virtual Server:While fast, this type uses thefasthttpprofile to provide some L7 awareness and optimization (like header insertion or small-scale multiplexing). Since the requirement specifically states HTTP optimization isnotrequired, the L4 variant is more efficient.

Standard Virtual Server:This is a full-proxy type. While it offers the most features (SSL offload, iRules, Compression), it processes traffic primarily in the TMOS software layer (or via high-level hardware assistance), which is "slower" than the pure hardware switching path of the Performance (L4) type.

Stateless Virtual Server:This is typically used for specific UDP/ICMP traffic where the system does not need to maintain a connection table. It is not appropriate for standard HTTP (TCP) applications requiring persistent sessions or stateful load balancing.

By choosingPerformance (Layer 4)with thefastL4profile, the organization ensures that the traffic is handled by the hardware acceleration chips, providing the lowest latency and highest throughput possible for their HTTP application.

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

When troubleshootingperformance and latency issueson BIG-IP, especially under peak load conditions, it is critical to identify whichVirtual Servers are consuming the most resources. This is a coredata plane analysis task.

BIG-IP provides multiple views of configuration and status, but only certain areas exposereal-time and historical traffic statisticsthat correlate directly with CPU usage and throughput.

Why Option C Is Correct:

Statistics > Module Statistics > Local Traffic > Virtual Serversprovides:

Real-time and cumulative statistics per Virtual Server

Metrics such as:

Bits in / Bits out

Packets in / Packets out

Current connections

Connection rate

Total requests

The ability toidentify high-traffic or high-connection Virtual Servers, which are the most likely contributors to elevated CPU utilization

These statistics allow the administrator toobjectively determine which Virtual Servers are the top consumers of system resourcesand therefore good candidates for migration to a dedicated BIG-IP device.

Why the Other Options Are Incorrect:

A. Local Traffic > Virtual Servers > Virtual Server List

Primarily aconfiguration view

Does not provide sufficient performance or utilization statistics to identify CPU-heavy Virtual Servers

B. System > Platform

Displayshardware-level informationsuch as CPU cores, memory, disk, and platform type

Does not break down utilization by Virtual Server

D. Local Traffic > Network Map

Provides alogical topology viewof Virtual Servers, pools, and pool members

Useful for understanding relationships, but not for identifying high-utilization Virtual Servers

Key Data Plane Concept Reinforced:

To diagnose performance problems and plan traffic redistribution, BIG-IP administrators must rely onModule and object-level statistics, not configuration screens. TheVirtual Server statistics viewis the authoritative location for identifyingtraffic hotspotsthat directly impact CPU and latency during peak events such as Black Friday.

===========

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

WithLeast Connections (member), BIG-IP attempts to send new connections to the pool member with the fewest current connections. In a perfectly “stateless” scenario (no affinity), this often trends toward a fairly even distribution over time.

However,persistence overrides load balancing:

When apersistence profileis applied, BIG-IP will continue sending a client (or client group) to thesame pool memberbased on the persistence record (cookie / source address / SSL session ID, etc.).

This means even if another pool member has fewer connections, BIG-IP may still select the persisted member to honor session affinity.

The result can beuneven active connection counts, even though the configured load balancing method is Least Connections.

Why the other options are not the best cause:

A. Priority Group Activation is disabledPriority Group Activation only affects selection when priority groups are configured; disabling it does not inherently create uneven distribution under Least Connections.

B. SSL Profile Server is appliedA server-side SSL profile affects encryption to pool members, but it does not by itself cause skewed selection across pool members. (Skew could happen indirectly if members have different performance/latency, but that’s not the primary, expected exam answer.)

D. Incorrect load balancing methodLeast Connections is a valid method and does not itself explain unevenness unless something is overriding it (like persistence) or pool members are not all eligible.

Conclusion:

Apersistence profileis the most common and expected reason that active connections becomeunevenly distributed, because persistencetakes precedence overthe Least Connections load-balancing decision.

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

Although remote authentication (LDAP, RADIUS, TACACS+) is acontrol-plane / management-planefeature, it directly affectsavailability and resiliency of administrative access, which is a critical operational HA consideration.

How BIG-IP Remote Authentication Works:

BIG-IP can authenticate administrators against:

LDAP

RADIUS

TACACS+

When remote authentication is enabled, BIG-IPby default relies on the remote serverfor user authentication

If the remote authentication server becomes unreachable, administrators may belocked outunless fallback is configured

Why “Fallback to Local” Is Required:

TheFallback to Localoption allows BIG-IP to:

Attempt authentication against theremote authentication server first

If the remote server isunreachable or unavailable, fall back to:

Local BIG-IP user accounts (admin, or other locally defined users)

This ensures:

Continuous administrative access

Safe recovery during:

Network outages

Authentication server failures

Maintenance windows

This behavior is explicitly recommended as abest practicein BIG-IP administration to avoid loss of management access.

Why the Other Options Are Incorrect:

A. Configure a second remote user directory

Provides redundancyonly if both directories are reachable

Does not help if remote authentication as a whole is unavailable

B. Configure a remote role group

Maps remote users to BIG-IP roles

Does not affect authentication availability

D. Set partition access to “All”

Controls authorization scope after login

Has no impact on authentication success

Key Availability Concept Reinforced:

To maintainadministrative access resiliency, BIG-IP administrators should always enableFallback to Localwhen using remote authentication. This prevents lockouts and ensures access even during authentication infrastructure failures.

===========

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

In anActive/StandbyBIG-IP design, application availability during failover depends on both units havingequivalent data-plane connectivityfor the networks that carry application traffic. Specifically:

VLANs are bound to specific interfaces (and optionally VLAN tags).

Floating self IPs / traffic groupsmove to the new Active device during failover.

For traffic to continue flowing after failover, the new Active device must have thesame VLANs available on the correct interfacesthat connect to the upstream/downstream networks.

What the symptom tells you:

Traffic works when Device A is Active

Traffic fails when Device B becomes Active

Failback immediately restores traffic

This pattern strongly indicates theStandby unit does not have the VLAN connected the same way(wrong physical interface assignment), so when it becomes Active, it owns the floating addresses but cannot actually pass traffic on the correct network segment.

WhyInterface mismatchis the best match:

If theActiveunit is already working, its interface mapping is correct.

The fix is to make theStandbyunit’s VLAN/interface assignment match the Active unit.

That corresponds tochanging the Standby device interface to 1.1.

Why theTagoptions are less likely here (given the choices and the exhibit intent):

Tag issues can also break failover traffic, but the question/options are clearly driving toward the classic HA requirement:consistent VLAN-to-interface mapping on both devicesso the data plane remains functional after the traffic group moves.

Conclusion:To avoid an outage on the next failover, the BIG-IP Administrator must ensure the Standby device uses thesame interface (1.1)for the relevant VLAN(s) that carry the application traffic, so when it becomes Active it can forward/receive traffic normally.

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

In BIG-IP, atrunkis a Layer 2 network object used to aggregate multiple physicalinterfacesinto a single logical link. This aggregation providesincreased bandwidthandlink resiliency, commonly in conjunction with LACP.

Key concepts that apply here:

Trunks are managed under the/net trunktmsh hierarchy

Physical interfaces are added or removed using themodifycommand

Thecreatecommand is used only when defining a brand-new trunk, not when updating an existing one

Because the trunk already exists and the goal is toadd interfaces, the correct operation is:

tmsh modify /net trunk trunk_A interfaces add {1.3 1.4}

This command:

Modifies the existing trunk named trunk_A

Adds interfaces 1.3 and 1.4 to the trunk

Immediately increases available bandwidth and redundancy

Why the Other Options Are Incorrect

Buses the /sys hierarchy, which is not used for trunks

Cattempts to create a trunk that already exists

Duses an incorrect hierarchy and an incorrect operation

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.