You are a DNS server, and you receive a request for the A record for www.foo.com. You have nothing in your cache except for the IP address of one of the DNS root servers (1.2.3.4). What is the first DNS request you send? Be sure to specify (a) the server you send the request to, (b) what you are querying for, and (c) what type of record you are asking for. Enter your answer here Q3.2 DNS queries (cont.) 6 Points Continuing the previous question, you finally hear back from the authoritative server for foo.com (whose IP address is 5.6.7.8) that www.foo.com is in fact a CNAME for www.bar.foo.com. Imagine you now have all of the answers from the lookups you just performed cached. What is the next DNS request you send? Be sure to specify (a) the server you send the request to, (b) what you are querying for, and (c) what type of record you are asking for. O 1 F3 Assignment 6: Graph Algorithms II Q3.3 Open resolvers 5 Points Enter your answer here Q3.4 CDNs and DNS 5 Points Open DNS Resolvers (such as Google's 8.8.8.8) are DNS servers that will respond to DNS queries from any Internet host (as opposed to private DNS servers, which typically only respond to requests from hosts in their network). However, Open DNS Resolvers are often viewed as a potential security threat. Why? What kind of security attack would involve an Open DNS Resolver? Enter your answer here Q4 TCP 17 Points 4 Q4.1 Stop-and-wait Recall our discussion of Content Distribution Networks (CDNs), and how they often use DNS to return a "close" server to a requesting client. How do they do this? Why might clients that choose to use Open DNS Resolvers be difficult for CDNs to handle in this manner? DOD 000 F4 5 F5 gradescope.com 65 Submit Midterm 2 | Gradescope 6 MacBook Air F6 7 7 Y F7 8 ! 11 F8 C 9 (31) WhatsApp F9 C 0 4 F10