F5 Networks F5CAB2 Exam Dumps

By default, when a pool member is marked 'down' by a monitor, the BIG-IP system stops sending new connections to that member, but it typically allows existing connections to time out naturally (or resets them depending on profile settings).

Action on Service Down: This setting is configured at the Pool level.

Reselect: When set to Reselect, if a pool member is marked down, the BIG-IP system will immediately attempt to pick a different available pool member for any existing, active connections associated with the failed member.

Client Experience: This is used to maintain the user session by transparently moving the traffic to a healthy server without the client needing to re-establish the connection to the Virtual Server.

Although remote authentication (LDAP, RADIUS, TACACS+) is a control-plane / management-plane feature, it directly affects availability 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-IP by default relies on the remote server for user authentication

If the remote authentication server becomes unreachable, administrators may be locked out unless fallback is configured

Why ''Fallback to Local'' Is Required:

The Fallback to Local option allows BIG-IP to:

Attempt authentication against the remote authentication server first

If the remote server is unreachable 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 a best practice in BIG-IP administration to avoid loss of management access.

Why the Other Options Are Incorrect:

A . Configure a second remote user directory

Provides redundancy only 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 maintain administrative access resiliency, BIG-IP administrators should always enable Fallback to Local when using remote authentication. This prevents lockouts and ensures access even during authentication infrastructure failures.

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In BIG-IP, a trunk is a Layer 2 network object used to aggregate multiple physical interfaces into a single logical link. This aggregation provides increased bandwidth and link resiliency, commonly in conjunction with LACP.

Key concepts that apply here:

Trunks are managed under the /net trunk tmsh hierarchy

Physical interfaces are added or removed using the modify command

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

Because the trunk already exists and the goal is to add 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

B uses the /sys hierarchy, which is not used for trunks

C attempts to create a trunk that already exists

D uses an incorrect hierarchy and an incorrect operation

In this scenario, two specific High Availability and Persistence requirements must be met to ensure session continuity during a failover.

Persistence Mirroring: By default, persistence records (which map a client to a specific server) exist only on the memory of the active BIG-IP. If a failover occurs, the standby unit has no knowledge of these sessions and will re-load-balance the client, likely to a different server. Enabling Persistence Mirroring ensures that the persistence table is synchronized in real-time to the standby peer.

Match Across Services: The requirement specifies that the session must persist across both HTTP and FTP. These are different Virtual Servers (and likely different ports). The Match Across Services setting in the persistence profile allows the BIG-IP to use the same persistence record for any Virtual Server that shares the same IP address and pool, regardless of the service port.

This question tests understanding of Priority Group Activation (PGA) and how BIG-IP determines which pool members are eligible to receive traffic.

Key BIG-IP Priority Group Concepts:

Higher priority group numbers = higher priority

BIG-IP will only send traffic to the highest priority group that meets the Priority Group Activation condition

Lower priority groups are activated only when the condition is met

Only available (green) members count toward the activation threshold

Configuration from the Exhibit:

Priority Group Activation: Less than 2 available members

Pool Members and Status:

Pool Member

Priority Group

Status

serv1

2

Active (available)

serv2

2

Inactive (down)

serv3

1

Active (available)

serv4

1

Active (available)

Step-by-Step Traffic Decision:

BIG-IP first evaluates the highest priority group (Priority Group 2)

Priority Group 2 has:

serv1 available

serv2 unavailable

Total available members = 1

Activation rule is Less than 2 available members

Condition is true (1 < 2)

BIG-IP activates the next lower priority group (Priority Group 1)

Traffic is now sent to:

serv1 (Priority Group 2)

serv3 and serv4 (Priority Group 1)

Final Result:

Traffic is distributed to serv1, serv3, and serv4

Why the Other Options Are Incorrect:

A -- Ignores activation of the lower priority group

B -- serv4 is also active and eligible

C -- serv2 is down and cannot receive traffic

Key Data Plane Concept Reinforced:

Priority Group Activation controls when lower-priority pool members are allowed to receive traffic, based strictly on the number of available members in the higher-priority group. In this case, the failure of one high-priority member caused BIG-IP to expand traffic distribution to lower-priority members to maintain availability.

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