a$.$ Which of the statements about protocol architecture are correct? check all that apply.

i$.$ Packet network protocol is structured into layers such as ISO $7-$layer or IP $4-$layer

ii$.$ Protocol syntax refers to structure and information fields in control and data

packets.

iii. Protocol semantics refers to actions to be performed on each packet.

iv$.$ Algorithms for functions such as routing are not a part of the core protocol

specification.

v$.$ Routing algorithms used in the IP spec include Dijkstra and Bellman $$ ford.

b$.$ Which of the statements about medium access control $($MAC$)$ are correct? Check all that

apply:

i$.$ Random access MAC protocol are those which allow users to transmit at any time.

ii$.$ Random access MAC protocols require collision backoff to ensure stability.

iii. Ethernet MAC scales well with link speed and distance$/$network span.

iv$.$ CSMA doesn$$t work on wireless channels because collisions are hard to detect.

v$.$ Collision avoidance $($CA$)$ in $802\mathrm{.}11$ MAC completely prevent collisions on the

channel.

c$.$ What is the main difference between routing and forwarding? Check all correct

statements.

i$.$ Routing is based on shortest paths while forwarding is based on spanning tree.

ii$.$ They are different words for the same idea.

iii. Routing is network$-$wide process, while forwarding is a local operation.

iv$.$ Routing is the process of finding paths, forwarding is the process of sending

packets along a path.

d$.$ Which of the following about multicast and anycast is$/$are true?

i$.$ Both IP multicast and anycast require special support from routers.

ii$.$ IP anycast can easily use TCP as a transport protocol to achieve reliability.

iii. Reliable IP multicast protocols typically use ACKs to confirm receipt of data.

iv$.$ Reliable multicast protocols can recover from missing data by having parties other

than the original sender retransmit the data.

e$.$ Which of the following is$/$are true about wireless networks?

i$.$ All wireless networks must use access points.

ii$.$ The sender can always detect a collision without feedback from receiver.

iii. Collisions are minimized when RTS$/$CTS mechanisms are used.

iv$.$ TCP congestion control mechanisms work poorly in wireless environments if they

do not perform any type of link$-$layer retransmission.

v$.$ Wireless networks generally have higher loss rates than that in wired networks.

f$.$ Which of the following is$/$are true about routers?

i$.$ Routers reassemble IP fragments if the next link can handle the full datagram.

ii$.$ Routers can arbitrarily drop packets if they want.

iii. Routers cannot change the IP packets they forward at all.

iv$.$ On a router with many $1$ Gbps ports, the router backplane can only handle $1$ Gbps

on the shared bus, leading to potential congestion.