When a BIG-IP administrator manually disables a pool member, it is a graceful action designed to take a server out of service without disrupting active users. The BIG-IP system immediately stops sending new connections to that specific member. However, it allows all existing connections, including persistent ones, to continue until they are closed by the client/server or their timeout expires. The other active members in the pool are unaffected and continue to accept new connections and process their existing ones. Therefore, all pool members (including the one being disabled) continue to process their persistent connections.

A. The disabled pool member stops processing persistent connections.

This is incorrect. The "Disabled" state specifically allows existing and persistent connections to continue until they complete naturally.

C. The disabled pool member stops processing existing connections.

This describes the "Forced Offline" state, which immediately terminates all existing connections to the member, not the "Disabled" state.

D. All pool members stop accepting new connections.

This is incorrect. Only the single, manually disabled pool member stops accepting new connections; the other members in the pool continue to function normally.

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1. F5 Networks Knowledge Base, K13310: Disabling nodes or pool members for maintenance (BIG-IP LTM)

Section: "Disabling a pool member or node"

Content: "When you disable a pool member or node, the BIG-IP system allows existing connections to time out before the system takes the resource out of service... The Disabled state allows existing connections to time out, but the system accepts no new connections." This supports that existing/persistent connections continue, making option B correct and options A and C incorrect.

2. F5 BIG-IP LTM Concepts Guide, v15.1

Chapter: "Pools"

Section: "Setting the availability of a pool member"

Content: "Disabling a pool member or node: This state is initiated by the user. When you disable a pool member or node, it continues to process any current connections, but accepts no new connections. This is considered a graceful shutdown of a server." This directly confirms that the disabled member continues processing current connections and that other members are not affected, validating B as the correct answer and invalidating A, C, and D.