- What is the goal of the Internetworking layer?
Move packets across multiple hops from a source to destination computer
Move packets across a single physical connection
Deal with web server failover
Deal with encryption of sensitive data
- How many different physical links does a typical packet cross from its source to its destination on the Internet?
- Which of these is an IP address?
- Why is it necessary to move from IPv4 to IPv6?
Because IPv6 has smaller routing tables
Because IPv6 reduces the number of hops a packet must go across
Because we are running out of IPv4 addresses
Because IPv6 addresses are chosen by network hardware manufacturers
- What is a network number?
A group of IP addresses with the same prefix
The GPS coordinates of a particular LAN
The number of hops it takes for a packet to cross the network
The overall delay packets experience crossing the network
- How many computers can have addresses within network number "218.78"?
- How do routers determine the path taken by a packet across the Internet?
The routes are controlled by the IRG (Internet Routing Group)
Each router looks at a packet and forwards it based on its best guess as to the correct outbound link
Each router sends all packets on every outbound link (flooding algorithm)
Each router holds on to a packet until a packet comes in from the destination computer
- What is a routing table?
A list of IP addresses mapped to link addresses
A list of IP addresses mapped to GPS coordinates
A list of network numbers mapped to GPS coordinates
A list of network numbers mapped to outbound links from the router
- How does a newly connected router fill its routing tables?
By consulting the IANA (Internet Assigned Numbers Authority)
By downloading the routing RFC (Request for Comments)
By contacting the Internet Engineering Task Force (IETF)
By asking neighboring routers how they route packets
- What does a router do when a physical link goes down?
Throws away all of the routing table entries for that link
Consults the Internet Map (IMAP) service
Does a Domain Name (DNS) looking for the IP address
Sends all the packets for that link back to the source computer
- Why is it good to have at least a "two-connected" network?
Because routing tables are much smaller
Because it removes the need for network numbers
Because it supports more IPv4 addresses
Because it continues to function even when a single link goes down
- Do all packets from a message take the same route across the Internet?
- How do routers discover new routes and improve their routing tables?
Each day at midnight they download a new Internet map from IMAP
They periodically ask neighboring routers for their network tables
They randomly discard packets to trigger error-correction code within the Internet
They are given transmission speed data by destination computers
- What is the purpose of the "Time to Live" field in a packet?
To make sure that packets do not end up in an "infinite loop"
To track how many minutes it takes for a packet to get through the network
To maintain a mapping between network numbers and GPS coordinates
To tell the router the correct output link for a particular packet
- How does the "traceroute" command work?
It sends a series of packets with low TTL values so it can get a picture of where the packets get dropped
It loads a network route from the Internet Map (IMAP)
It contacts a Domain Name Server to get the route for a particular network number
It asks routers to append route information to a packet as it is routed from source to destination
- About how long does it take for a packet to cross the Pacific Ocean via an undersea fiber optic cable?
- On a WiFi network, how does a computer get an Internetworking (IP) address?
Using the DHCP protocol
Using the DNS protocol
Using the HTTP protocol
Using the IMAP protocol
- What is Network Address Translation (NAT)?
It looks up the IP address associated with text names like "www.dr-chuck.com"
It allows IPv6 traffic to go across IPv4 networks
It looks up the best outbound link for a particular router and network number
It reuses special network numbers like "192.168" across multiple network gateways at multiple locations
- How are IP addresses and network numbers managed globally?
There are five top-level registries that manage network numbers in five geographic areas
IP addresses are assigned worldwide randomly in a lottery
IP addresses are assigned by network equipment manufacturers
IP addresses are based on GPS coordinates
- How much larger are IPv6 addresses than IPv4 addresses?
They are the same size
IPv6 addresses are 50% larger than IPv4 addresses
IPv6 addresses are twice as large as IPv4 addresses
IPv6 addresses are 10 times larger than IPv4 addresses
- What does it mean when your computer receives an IP address that starts with "169.."?
Your connection to the Internet supports the Multicast protocol
The gateway is mapping your local address to a global address using NAT
There was no gateway available to forward your packets to the Internet
The gateway for this network is a low-speed gateway with a small window size
- If you were starting an Internet Service Provider in Poland, which Regional Internet Registry (RIR) would assign you a block of IP addresses.