Names, Handshakes and Trade-offs: teacher key

The Internet, grade 9 edition, written for 9th grade. Trace a DNS question from the root down to the final answer, watch a secure connection open in a set order, and see what a content delivery network costs. Then meet the people who write the standards.

Read the book. Print this page for the key.

Questions and answers

1. What does a root name server do with a question about a .com site?
   • Gives the final answer
   • Refers it to the name server for the top-level domain (answer)
   • Deletes it
2. What is the time-to-live for?
   • How long a resolver remembers a recent DNS answer (answer)
   • How long a cable lasts
   • How fast a packet travels
3. In what order do the early steps of a secure web page come?
   • TLS handshake, TCP handshake, DNS lookup
   • DNS lookup, TCP handshake, TLS handshake (answer)
   • TCP handshake, DNS lookup, TLS handshake
4. What can happen to a website that depends on a CDN?
   • It can stop working if the CDN goes down or is blocked (answer)
   • It always loads faster
   • It gets more IP addresses
5. Who can help write internet standards at the IETF?
   • Anyone, as a volunteer (answer)
   • Only company members
   • Only governments

Words

• resolver: DNS asker
• authoritative: giving final answers
• encryption: scrambling data
• grapnel: hook-like tool
• registries: public lists