What F5CAB2 Questions and Answers feature?

This scenario combines session continuity, multiple protocols (HTTP and FTP), and HA failover behavior, which directly implicates persistence handling across devices and services.

Key Requirements Breakdown

Same pool member for entire session

Session must survive failover

Session must span multiple services (HTTP and FTP)

Why Persistence Mirroring + Match Across Services Is Required

Persistence Mirroring

Ensures persistence records are synchronized from the active BIG-IP to the standby BIG-IP.

Without mirroring:

After failover, the standby device has no persistence table

Clients are load-balanced again

Sessions break, forcing users to restart

Persistence mirroring is essential for session continuity during failover

Match Across Services

Allows a single persistence record to be shared across multiple virtual servers / protocols

Required when:

HTTP and FTP must use the same pool member

Multiple services are part of a single application session

Together, these settings ensure:

Persistence survives device failover

Persistence is honored across HTTP and FTP

Why the Other Options Are Incorrect

A. Cookie persistence and session timeoutCookie persistence only applies to HTTP and does not address FTP or failover synchronization.

B. Stateful failover and Network Failover detectionStateful failover applies to connection state, not persistence records, and does not link HTTP and FTP sessions.

D. SYN-cookie insertion threshold and connection low-water markThese are DoS / SYN flood protection settings, unrelated to persistence or HA behavior.

When establishing a redundant pair, each device must know where to send its health heartbeats and sync data.

The Peer IP: The Failover Peer IP is the IP address belonging to the other BIG-IP device in the HA pair. This is typically a34 Self-IP on a dedicated "HA" or "Internal" VLAN, or the Management IP.

Purpose: It identifies the destination for the "Heartbeat" (the "Are you alive?" check).

Setup Context: During the initial setup, you tell Device A to look for Device B at its "Failover Peer IP," and you tell Device B to look for Device A at its respective "Failover Peer IP."

In BIG-IP LTM, health monitors are used to determine the availability of pool members and directly influence traffic flow decisions in the data plane.

Key characteristics of the default HTTP monitor according to BIG-IP Administration Data Plane Concepts:

Sends an HTTP request (typically GET /)

Expects an HTTP response code of 200 OK

Any response other than 200 is treated as a monitor failure

A failed monitor causes the pool member to be marked offline (down)

In this scenario:

Two pool members return 404 Not Found

A 404 response indicates that the requested object was not found

This does not meet the success criteria of the default HTTP monitor

These two members are therefore marked offline

One pool member returns 200 OK

This matches the expected response

The member is marked online

Resulting Pool Member Availability:

2 members: Offline

1 member: Online

Why the Other Options Are Incorrect:

B – 404 responses are not considered healthy by the default HTTP monitor

C – At least one member responds with the expected 200 OK

D – Members returning 404 responses fail the monitor and cannot be marked online

Key Data Plane Concept Reinforced:

BIG-IP health monitors make binary availability decisions based strictly on configured success criteria. For HTTP monitors, response codes matter—404 is a failure, even if the service is technically reachable.

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