Layers, Routes and Long Waits: teacher key

The Internet, grade 10 edition, written for 10th grade. The internet works in layers, and big networks swap routes with BGP. Learn how a certificate ties a name to its keys, why the first request to a site takes longer, how a few repair ships keep cables working, and what early dreamers imagined.

Read the book. Print this page for the key.

Questions and answers

1. What do neighbouring networks use BGP to swap?
   • Domain names
   • Network reachability information (answer)
   • Web pages
2. What does a digital certificate tie to a website's keys?
   • Its domain name (answer)
   • Its repair ship
   • Its cable
3. What makes the first request to a site take longer?
   • A long cable
   • A free certificate
   • A DNS lookup, a TCP handshake and TLS negotiation (answer)
4. How long can repair delays last, according to ITU?
   • Minutes
   • Weeks or months (answer)
   • Exactly one day
5. Why can a cable repair wait?
   • Few ships can repair undersea cables (answer)
   • Cables repair themselves
   • Repairs are free

Words

• autonomous: self-governing
• certificate: proof of identity
• handshake: connection setup
• hypertext: linked text
• exchange: swapping place