F5 Networks F5CAB2 Exam - Topic 4 Question 4 Discussion

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

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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