Above servers refused to provide IP addresses for yahoo.com, google.com, et al
DNS messages are sent via UDP
Destination port of request and source port of response are both 53
Destination IP address is 71.252.0.12, same as the server used by nslookup by default
One query of type “A” and one of type “HTTPS” are made; no answers present
Response message contains two answers: one type CNAME, one type HTTPS
Subsequent TCP SYN packet dest address corresponds to second IP address given by DNS response
GET http://www.ietf.org request elicits 301 Moved Permanently response with “Locaction: https://www.ietf.org” after which two more DNS requests are made, one of type A and one of type HTTPS, which appear identical to the requests made previously
Destination port of request and source port of response are both 53
Destination IP address is 71.252.0.12, the default local DNS server
DNS query message is of type “A” and contains no answers
DNS response message contains 3 answers: www.mit.edu has a CNAME record pointing to www.mit.edu.edgekey.net, which has a CNAME record pointing to e9566.dscb.akamaiedge.net, which has a type A record pointing to the IP address 104.106.237.16
Destination IP address is 71.252.0.12, the default local DNS server
DNS query message is of type “NS” and contains no answers
DNS response message provides nameserver dcsb.akamaiedge.net; no IP address is provided
Destination IP address is 2.16.40.64, corresponding to that of an authoritative nameserver for mit.edu, use5.akam.net (command run was nslookup www.aiit.or.kr use5.akam.net)
DNS query is of type “A” and contains no answers
No answers are provided; response was “Refused” (it appears that standard practice is for an authoritative nameserver to respond “Refused” to queries for any domain names for which it is not authoritative; perhaps at the time this lab was created MIT and AIIT shared authoritative DNS servers (see this ServerFault post). Some geographically close schools did appear to share authoritative nameservers, for example MIT and Harvard, and W&M and ODU)
