F5 Networks F5CAB2 Exam Questions Instant Access

Question 1

Which statement is true concerning the default communication between a redundant pair of BIG-IP devices?

ACommunication between the systems cannot be effected by port lockdown settings.

BData for both connection and persistence mirroring are shared through the same TCP connection.

CRegardless of the configuration, some data is communicated between the systems at regular intervals.

DConnection mirroring data is shared through the serial fail over cable unless network failover is enabled.

Answer : C

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).

Question 2

The BIG-IP Administrator needs to ensure that if a pool member is marked down by the monitor, the BIG-IP system sends existing connections to another available pool member. Which task should the BIG-IP Administrator perform to meet this goal?

AReconfigure the pool monitor to mark the member as UP

BEnable mirroring within the persistence profile

CSet Action on Service Down setting under the Virtual Server configuration to reselect

DSet Action on Service Down setting under the pool configuration to reselect

Answer : D

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.

Question 3

Which two statements describe differences between the active and standby systems? (Choose two.)

AMonitors are performed only by the active system.

BFailover triggers only cause changes on the active system.

CVirtual server addresses are hosted only by the active system.

DConfiguration changes can only be made on the active system. (Incorrect)

EFloating self-IP addresses are hosted only by the active system.3536

Answer : C, E

The primary distinction between Activ41e and Standby units revolves around which unit is currently processing traffic.

Traffic Objects (C & E): The unit in the 43Active state is the only one that answers ARP requests for Virtual Server addresses and Floating Self-IPs. The Standby unit remains 'quiet' for these addresses to avoid IP conflicts on the network.

Monitors (A - False): Both the Active and Standby units perform health monitors on pool members by default. This ensures that the Standby unit is ready to take over with an up-to-date view of the pool's health.

Failover (B - False): A failover trigger (like a VLAN fail-safe) causes the Active unit to go Standby and the Standby unit to go Active; it affects both.

Management (D - False): Configuration changes can technically be made on either unit (though it is best practice to make them on the Active unit) and then synchronized to the peer.

Question 4

Which statement is true concerning iRule events?

AAll iRule events relate to HTTP processes.

BAll client traffic has data that could be used to trigger iRule events.

CAll iRule events are appropriate at any point in the client-server communication.

DIf an iRule references an event that doesn't occur during the client's communication, the client's connection will be terminated prematurely.

Answer : B

iRules are event-driven scripts that allow for advanced traffic manipulation.

Universality of Events: Every packet that passes through t21he BIG-IP data plane triggers events. Even non-HTTP traffic triggers events such as CLIENT_ACCEPTED (when the TCP connection is established22) or CLIENT_DATA (when raw data is received). Therefore, all client traffic---regardless of protocol---has data that can trigger an iRule event.

Event Specificity: Events are not universal (Option C is false). For example, HTTP_REQUEST only occurs after a full HTTP header is parsed. You cannot trigger an HTTP_RESPONSE event before a request has been sent to a server.

Protocol Agnostic: iRules are not limited to HTTP (Option A is false); they can handle TCP, UDP, DNS, FTP, SIP, and more.

Error Handling: If an iRule references an event that never triggers (e.g., an HTTP_REQUEST event in a purely TCP virtual server), the iRule code for that event simply never executes. It does not terminate the connection (Option D is false).

Question 5

A BIG-IP is configured with a pool member located on a different subnet that is not local to the BIG-IP. To ensure that the return traffic from the pool member is sent to the client through the BIG-IP, a Source NAT (SNAT) is used and configured for SNAT Automap. The BIG-IP has a default gateway on the external VLAN, a floating and non-floating self-IP address on each VLAN, and a management address. Which IP address will the BIG-IP use as the source address for the traffic to the pool member when client traffic is sent through the virtual server?

AThe source address will be the first address available in the list of self-IPs.

BThe source address will be the floating self-IP address on the egress VLAN.

CThe source address will be the non-floating self-IP address on the egress VLAN.

DThe source address will be the management IP address.

Answer : B

SNAT Automap is a feature that automatically selects a self-IP address to use as the source address for translated packets. The selection logic follows a strict hierarchy to ensure that traffic is routable back to the BIG-IP:

Egress VLAN Priority: The BIG-IP first looks at the VLAN through which the traffic is exiting toward the pool member (the egress VLAN).

Floating Self-IP Preference: If the egress VLAN has a floating self-IP address, the BIG-IP will always prefer it for SNAT Automap. This is critical for High Availability (HA) because, during a failover, the floating IP moves to the new active device, allowing existing connections to be maintained or correctly timed out.

Non-Floating Fallback: If no floating self-IP is available on the egress VLAN, the system will use a floating self-IP from a different VLAN. If no floating IPs exist at all, it will then fall back to the non-floating self-IP.

Key Data Plane Concept:

The management IP is never used for data plane traffic. In this scenario, since the administrator has configured a floating self-IP, that specific address becomes the source for all SNAT Automap traffic leaving that VLAN to ensure symmetric routing during HA events.

Question 6

and their status/statistics]

To increase available bandwidth of an existing Trunk, the BIG-IP Administrator is adding additional interfaces. Which command should the BIG-IP Administrator run from within bash shell?

Atmsh modify /sys trunk trunk_A interfaces add {1.3 1.4}

Btmsh create /net trunk trunk_A interfaces add {1.3 1.4}

Ctmsh create /sys trunk trunk_A interfaces add {1.3 1.4}

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

Answer : D

Configuring networking objects in BIG-IP requires using the correct TMSH module path and verb.

Module Path: Trunks are networking objects, so they reside under the /net module, not /sys.

Verb: Since the trunk already exists, the modify verb must be used to update its properties rather than create.

Syntax: The correct syntax to append physical interfaces to an existing trunk is tmsh modify /net trunk [name] interfaces add { [port list] }.

Data Plane Impact: Adding interfaces to a trunk (Link Aggregation) increases the total aggregate bandwidth available to the system and provides additional hardware redundancy.

Question 7

A BIG-IP Administrator assigns the default http health monitor to a pool that has three members listening on port 80. When the administrator connects to each pool member via the CURL utility, two of the members respond with a status of 404 Not Found while the third responds with 200 OK. What will the pool show for member availability?

ATwo members offline and one member online

BTwo members online and one member offline

CAll members offline

DAll members online

Answer : D

The behavior of a health monitor is determined by its Send String and Receive String.

Default HTTP Monitor: The pre-configured default HTTP monitor on a BIG-IP system has an empty Receive String.

Success Criteria: When the Receive String is blank, the BIG-IP system considers the health check successful if it receives any valid HTTP response from the server.

Status Code Interpretation: Because a 404 Not Found is a valid HTTP status code (it is a properly formatted response from a running web server process), the BIG-IP interprets this as the application being 'alive'.

Result: All three members (including the two returning 404s and the one returning 200) will be marked as UP/Available (Green).

F5 Networks BIG-IP Administration Data Plane Concepts F5CAB2 Exam Questions