Function getIpvalue(clientIP)  '得到客户端 的IP转换成长整型，返回值getIpvalue
On Error Resume Next
Dim strIp, array_Ip
strIp=0
array_Ip = Split(clientIP,".")
If UBound(array_Ip)<>3 Then
getIpvalue=0
Exit Function
End If
For i=0 To 3
strIp=strIp+(CInt(array_Ip(i))*(256^(3-i)))
Next
getIpvalue=strIp
If Err Then getIpvalue=0
End Function

  clientIP=request.ServerVariables("REMOTE_HOST")
IpValue=getIpvalue(clientIP)

strSql="select top 1 City from [Ipaddress]  where "&IpValue&" between Ip1 and Ip2"
Set RsIp=conn.execute(strSql)
If RsIp.bof and RsIp.eof then
UrlCity="未知"
Else
UrlCity=RsIp.Fields.Item("City").Value
End If

         if instr(UrlCity,"广州")<>0 then response.Redirect("http://code.knowsky.com")
        if instr(UrlCity,"深圳")<>0 then response.Redirect("http://moban.knowsky.com")
        if instr(UrlCity,"上海")<>0 then response.Redirect("http://font.knowsky.com")

由于IP库超过1M，所以上传不了，IP库网上很多，code.knowsky.com 就有下载。上面只是其中一种方法.