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=0(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（  ）。