![]() Clear the DNS cache in your host, as described above. ![]() 对于windows系统的电脑,输入命令ipconfig /flushdns清理DNS缓存 3.Tracing DNS with Wireshark Just like many Web browsers keep a cache of objects recently retrieved by HTTP,most hosts(e.g.,your personal computer)keep a cache of recently retrieved DNS records(sometimes called a DNS resolver cache).When DNS services need to be invoked by a host, that host will first check if the DNS record needed is resident in this host’s DNS cache if the record is found, the host will not even bother to contact the local DNS server and will instead use this cached DNS record.A DNS record in a resolver cache will eventually timeout and be removed from the resolver cache, just as records cached in a local DNS server will timeout. What is that name? (If there are more than one authoritative servers, what is the name of the first authoritative server returned by nslookup)? If you had to find the IP address of that authoritative name server, how would you do so? 2.The DNS cache on your computer Ģ.What is the IP address of the DNS server that provided the answer to your nslookup command in question 1 above?ģ.Did the answer to your nslookup command in question 1 above come from an authoritative or non-authoritative server?Ĥ.Use the nslookup command to determine the name of the authoritative name server for the iit.ac.in domain. As the image shows above,the IP address of is 103.21.124.10.
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