我跑步＆＃39; arp -a＆＃39;并收到以下消息：
apples-MacBook-Air-2:~ apple$ arp -a
hitronhub.home (192.168.0.1) at ac:20:2e:73:d4:42 on en0 ifscope [ethernet]
? (192.168.0.254) at 0:55:7b:b5:7d:f7 on en0 ifscope [ethernet]
? (192.168.0.255) at ff:ff:ff:ff:ff:ff on en0 ifscope [ethernet]
我想知道＆＃34; en0＆＃34;和＃34; ifscope [ethernet]＆＃34;字段意味着什么？