1Z0-078 practice question 4 of 15

Which two statements are true about load balancing using a database service in a RAC environment? (Choose two.)

Answer options

A: Client-side connect time load balancing works only if it uses a tnsnames entry specifying load BALANCE=yes.

B: Server-side connect time load balancing is done at the time of the initial connection attempt to the database service. Correct answer

C: Server-side load balancing connections are always distributed across instances based on the fastest response time for the service.

D: Client-side connect time load balancing is done at the time of the initial connection attempt to the database service. Correct answer

E: In client-side load balancing, the SCAN listener uses the Load Balancing Advisory to direct a connection request to the least loaded instance hosting the service.

Correct Answer:

B. Server-side connect time load balancing is done at the time of the initial connection attempt to the database service.; D. Client-side connect time load balancing is done at the time of the initial connection attempt to the database service.

Explanation

Connect-time load balancing can be performed either by the client or by the listener, but it occurs only when the initial connection is being made. Client-side CTLB (loadbalance=yes) randomly selects an address before contacting the listener (D). Server-side CTLB lets the listener choose an instance for the new session during the first handshake (B).

Why Incorrect

A – CTLB also works with EZCONNECT; it is not limited to tnsnames.ora entries. C – Server-side runtime load balancing (not connect-time) uses service response-time metrics; CTLB does not. E – The SCAN listener’s advisory-based routing is part of server-side load balancing, not client-side CTLB.

References

1. Oracle Net Services Administrator’s Guide 19c, ch. 12 “Load Balancing and Failover”, sections “Client-Side Connect-Time Load Balancing” and “Server-Side Connect-Time Load Balancing” (E96270-10).

2. Oracle Real Application Clusters Administration and Deployment Guide 19c, 7.2 “Using Services for Load Balancing” (F32770-10).

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