问答题
请说明SGSN配置的hostfile中，优先级和权重的含义。根据含义，假设用户分布负荷权重期望，判断220.211.57.1和220.211.57.2两个地址上om.bj用户量所占的百分比。
ADD I PV4DNSH: NM= "om .bj.m nc001 .m cc460.gprs", ADDRNUM= FOUR,
ADDR1 = "220.21 1 .57.1 ", ADDR2= "220.21 1 .57.2", PRI ORI TY1 = 20,
PRI ORI TY2= 10, WEI GHT1 = 2, WEI GHT2= 3;