F5CAB2 Exam Questions & Answers
BIG-IP Administration Data Plane Concepts • F5 Networks
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Sample F5CAB2 Questions
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A BIG-IP Administrator configures remote authentication and needs to ensure that users can still log in even when the remote authentication server is unavailable. Which action should the BIG-IP Administrator take in the remote authentication configuration to meet this requirement? (Choose one answer)
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.
An organization needs to deploy an HTTP application on a BIG-IP system. The requirements specify hardware acceleration to enhance performance, while HTTP optimization features are not required.
What type of virtual server and associated protocol profile should be used to meet these requirements? (Choose one answer)
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 the fastL4 profile, which allows the BIG-IP system to leverage the ePVA (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 the fasthttp profile to provide some L7 awareness and optimization (like header insertion or small-scale multiplexing). Since the requirement specifically states HTTP optimization is not required, 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 choosing Performance (Layer 4) with the fastL4 profile, 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.
A development team needs to apply a software fix and troubleshoot one of its servers. The BIG-IP Administrator needs to immediately remove all connections from the BIG-IP system to the back-end server. The BIG-IP Administrator checks the Virtual Server configuration and finds that a persistence profile is assigned to it. What should the BIG-IP Administrator do to meet this requirement?
Managing the lifecycle of a pool member requires understanding the difference between 'Disabled' and 'Forced Offline' states, especially when persistence is involved.
Disabled (User-Disabled): This state allows existing connections and persistent sessions to continue until they naturally time out or are closed by the client/server. It only prevents new sessions from being established.
Forced Offline: This state is more restrictive; it allows existing connections to complete but rejects all new connections, including those with existing persistence records.
Immediate Removal: Neither 'Disabled' nor 'Forced Offline' will instantly kill currently active, established TCP connections. To meet the requirement of 'immediately' removing all connections, the administrator must first set the member to Forced Offline (to prevent persistence from bringing in new traffic) and then use the command line (e.g., tmsh delete sys connection ss-server-addr [IP]) to clear the current connection table entries.
Which virtual server type is being configured in the screenshot? (Choose one answer.)
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).
and their status/statistics]
To increase the available bandwidth of an existing trunk, the BIG-IP Administrator plans to add additional interfaces. Which command should the BIG-IP Administrator run from within the bash shell? (Choose one answer)
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
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