Examine this tnsnames entry from a RAC configuration using a SCAN listener:
HR=(DESCRIPTION=
(LOAD_BALANCE =on)
(ADDRESS=(PROTOCOL=TCP)(HOST=cluster01-scan)(FORT=1521))
(CONNECT_DATA=(SERVICE_NAME=HRSRV)))
Which two statements are true about clients using this entry to connect? (Choose two.)
Client connection requests are automatically balanced across all IP addresses defined for the SCAN, ensuring efficient distribution of the load. Additionally, if the chosen SCAN listener is not available, the connection requests are automatically failed over to another available SCAN listener, which enhances the reliability and availability of the connection.
B,C - SCAN redirects to proper local listener which create`s a connection.
B,D is correct. Because C is wrong, client load is not balanced across all IPs.
B seems wrong because EZCONNECT doesn't use tnsnames.ora.
Answer: - Client connection requests are automatically failed over to another SCAN listener if the chosen SCAN listener is not available. When a client resolves the SCAN name it gets back all three SCAN VIPs. If the connection to the first VIP fails, the client transparently tries the next one, and so on, until one succeeds. Oracle Docs - Client connection requests are automatically balanced across all IP addresses defined for the SCAN. By default (and unless you’re using EZConnect), Oracle Net will round-robin or randomly pick among the three SCAN VIPs returned by DNS so that new connections are spread across them.