Oracle 11.2.0.2.0   ,   Linux AS 5.3   64bit   

[root@wsjrac01 etc]# cat   hosts
# Do not remove the following line, or various programs
# that require network functionality will fail.
127.0.0.1       localhost.localdomain localhost
::1             localhost6.localdomain6 localhost6

10.109.196.151    wsjrac01
10.1.1.151        wsjpri01
10.109.196.152    wsjvip01

10.109.196.153    wsjrac02
10.1.1.153        wsjpri02
10.109.196.154    wsjvip02

10.109.196.155    wsjrac03
10.1.1.155        wsjpri03
10.109.196.156    wsjvip03

#single client access name(scan)
10.109.196.157    wsjscan1
10.109.196.158    wsjscan2 

oracle 11g 的scan最多可以配置3个地址并对应域名。 SCAN是配置到DNS服务器上的，提供给RAC的仅仅是对应的DNS NAME   ,    这三个IP在DNS服务器上各对应同一个DNS NAME， 就是SCAN .