[cs615asa] HW4 graded

[Jan Schaumann]

Hello,

I've just sent out grades for HW4.  If you've not received an email with
your grade, please let me know asap.

Some of the things that seem to be worth noting as you hopefully revisit
the assignment:

- The packets captured on the DNS server should clearly show the query
  going to one of the root servers, then one of the gtld servers etc.

  Please review lecture 07 slides if it's not clear why this is
  necessary.

- The reverse lookup for the IP addresses of Facebook should likewise
  show the queries for the in-addr.arpa and ip6.arpa going to the root,
  the gtld, the RIRs nameservers etc.  (I don't believe a single one of
  you performed the reverse lookup of the IPv6 address!)

- Only about half of you answered the question of what DNS traffic you
  observed that you did not initiate yourself.  Please make sure to
  always read the assignment in full

- All the HTTP headers should be identified, not just a selection.
  Please review those that you did not identify.

While not part of the assignment, compare the difference in headers
between:

  ( printf "GET / HTTP/1.1\r\nHost: www.yahoo.com\r\n\r\n"; sleep 1; ) | \
        openssl s_client -connect www.yahoo.com:443

  ( printf "HEAD / HTTP/1.1\r\nHost: www.yahoo.com\r\n\r\n"; sleep 1; ) | \
        openssl s_client -connect www.yahoo.com:443

  curl -I https://www.yahoo.com

Why and how are they different?

-Jan