# Questions Week 11 Network Layer
## Objectives
## Outcomes
1. List the five layers of the network model.
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2. The network layer is comprised of two interacting layers, referred to as planes, what are those two planes?
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3. Briefly explain the difference between forwarding and routing in relation to the Network Layer.
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4. Give a brief explanation: In classical or traditional routing, how is the control plane logic determined?
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5. Give a brief explanation: In SDN (Software Defined Networking) hos is the control plane logic managed and distributed?
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6. In an IPv4 packet (see the IPv4) diagram posted in the Discord Channel (*notes-resources*), What is the TTL fields purpose?
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7. What happens to the value of this field each time it is forwarded to a new router?
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8. The Application layer packet is called a message. The Transport layer packer is called a segment, what is the Network layer packet referred to as?
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9. In a datagram, what is the theoretical maximum of this size in IPv4 according to the standard? What is the functional maximum size due to the MTU?
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10. Fill in the blank. Every host on the internet must have a ________ address.
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11. True or False. Correct the sentence if false. You have a subnet of 223.1.1.0/24. The IP 223.1.1.100 is a valid address in this subnet.
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12. True or False. Correct the sentence if false. You have a subnet of 223.1.1.0/24. The IP 223.1.2.100 is a valid address in this subnet.
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13. Fill in the blank. There are three private networks defined by RFC 1918 that routers will not route by default. They are 10.0.0.0/8, 172.16.0.0/16, and ______________ .
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14. Fill in the blank. Another name for a CIDR block is __________ (see RFC 950).
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15. On a local network, your home or at the university, what protocol do you use to obtain and IP address?
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16. Using that protocol in the previous question, what is the name of the system that hands out the IP address?
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17. Briefly explain what are the 4 steps between client and server to obtain an IP address (RFC 2131 section 3.1)?
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18. Briefly explain the concept of NAT, what it does, and where it is used (RFC 2663).
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19. Briefly explain the concept of a firewall, what it does and where on the network it is used.
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20. Looking at SDN match rules, from the class 11/03 recording Part I video — what are the three layers that an SDN controller can forward based on?
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21. Explain in what way SDN routing violates classical layer 3 based routing?
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22. Looking at RFC 1958, the original architectural principles of the internet involved moving the connection intelligence to the “edges.” Looking at technology like NAT, routing priority queues, and SDN, where do we see the network intelligence moving?
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23. In dealing with Routing Algorithm categories, the two general ones are: per-router and logically centralized. Explain the difference between the two methodologies behind these algorithms.
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24. Fill in the blank: A collection of routers under the control of one company or organization is referred to as ______________ system.
25. There are two primary routing protocols, OSPF (RFC 2328) and BGP (RFC 4271).
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26. Which Routing Algorithm is used to propagate route updates between Autonomous Systems (AS)?
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27. Which Routing Algorithm is used to propagate route updates inside Autonomous Systems (AS)?
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28. True or False. Correct if False. The government distributes Autonomous Systems Numbers.
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