某网络中PC1无法访问域名为www.aaa.cn的网站,而其他主机访问正常,在PC1上执行ping命令时有如下所示的信息: C:>ping www.aaa.cn Pinging www.aaa.cn[202.117.112.36] with 32 bytes of data: Reply from 202.117.112.36: Destination net unreachable. Reply from 202.117.112.36:Destination net unreachable. Reply from 202.117.1 12.36:Destination net unreachable. Reply from 202.1 17.112.36: Destination net unreachable. Ping statistics for 202.117.112.36: Packets: Sent=4,Received=4,Lost=O(0% loss), Approximate round trip tunes in milli-seconds: Minimum=0ms, Maximum=0ms, Average=0ms 造成该现象可能的原因是( )。