DCN_unit3

Ethernet provides which of the following services to the network layer

• reliable data transfer

• flow control

• error detection

• all of the mentioned

A host sends an IP datagram to another host in a different subnet. Which MAC address will it use as the destination in the Ethernet frame?

• Its own MAC address

• The destination host’s MAC address

• The DNS server’s MAC address

• The router’s interface MAC address

In a busy network with many nodes transmitting data, which multiple access protocol will provide the best efficiency and why?

• ALOHA – better for heavy load

• CSMA/CD – efficient and low cost

• TDMA – avoids collisions

• Pure ALOHA – always transmits immediately

Which situation would best justify using token passing over random access protocols?

• High-speed satellite link

• Heavy and predictable traffic load

• Low-latency IoT mesh

• Unreliable wireless medium

In CSMA/CD, after the 3rd collision, what is the probability that the value of K that a node chooses is 2?

• 0

• 0.125

• 0.25

• 0.33

A frame is sent with destination MAC FF-FF-FF-FF-FF-FF. What does this imply?

• It’s an ARP request or broadcast

• It’s a multicast message

• It’s a DNS lookup

• It’s a corrupted frame

What does a switch do if a frame’s destination MAC address is not in the MAC table?

• It drops the frame

• It queries ARP

• It floods the frame to all ports except the one it arrived on

• It sends it to the router

In a VLAN setup, what’s the function of the 802.1Q tag?

• Identify the VLAN ID of the frame

• Carry IP address info

• Determine CRC

• Resolve MAC addresses

An ARP query packet is encapsulated in

• a link-layer frame addressed to a specific adapter

• a link-layer broadcast frame

• none of the mentioned

• an IP datagram

What is the maximum efficiency of slotted ALOHA?

• 100%

• 50%

• 18%

• 37%