Explanation:
Only local naming method can be used with Oracle Connection Manager to filter client requests. Implementation a very simple TCP/IP network may induce you to choose answer A, but one of the requirements for Oracle Connection Manager is local naming. Incorrect Answer:
1: Not host, but only local naming method can be used for Oracle Connection Manager.
3: Only local method can be used with Oracle Connection Manager to filter client requests.
4: Both host and local naming methods cannot be used with Oracle Connection Manager to filter client requests. Only local method can be used.
Reference:
OCP Oracle 9i Database: Fundamentals II Exam Guide, Rama Velpuri, p. 28-29
Chapter 2: Basic Oracle Net Architecture

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