dns的UCP和ICMP有什么关系？UDP 137端口又是什么？

2bedodo

我在查询一个地址无效的情况下snoop了一下：
ns1.mydns.net.cn ->; h187.he.net.tw DNS C www.he.com.tw. Internet Addr ?
h187.he.net.tw ->; ns1.mydns.net.cn ICMP Destination unreachable (UDP port 53 unreachable)
h187.he.net.tw ->; ns1.mydns.net.cn NBT NS Query Request for *..............[0], Success
ns1.mydns.net.cn ->; h187.he.net.tw ICMP Destination unreachable (UDP port 137 unreachable)
h187.he.net.tw ->; ns1.mydns.net.cn NBT NS Query Request for *..............[0], Success
重复直到超时。
我不玉理解了，我发的UDP53请求，为什么对方响应icmp不可达？而且紧接着更响应UDP137不可达？那好象是NETBIOS name server的端口呀。谁碰到过的？是不是网络问题？为什么UDP和ICMP有关系？

2bedodo

我似乎查到了原因：
http://support.microsoft.com/default.aspx?kbid=325122

If a firewall or a router is blocking TCP or User Datagram Protocol (UDP) port 53, the error indicates the reason for the failing Domain Name System (DNS) queries.

The ICMP packet is sent as a response to a DNS name query by using TCP/UDP port 53. To troubleshoot this problem, you can use the tracert command to the destination host. Check the source address for the ICMP packet to identify the router that is sending the packet. In the Detail pane of Network Monitor, you can see the Internet Protocol (IP) header, which displays information about the IP address of the router or the node from where the packet is coming. Contact the router or the firewall administrator to open the filtered port.
可能对方有防火墙阻止了我对其后DNS的访问，这些信息是这个防火墙给出的。
大家看看有没有道理？