Physical and Link Layer Issues

Question 1

What are the different types of signal modulation?

Answer 1

• Amplitude Modulation (AM)
• Frequency Modulation (FM)
• Phase Modulation (PM)

Question 2

What is the formula for time to deliver a message of bits?

Answer 2

Total Time = Transmission Time + Propagation Time

• Transmission Time = 1 time unit per bit
• Propagation Time (bit) = Only applicable for last bit

Question 3

What are two problems with having a single large LAN?

Answer 3

• All broadcast traffic goes to every adapter
• Privacy and security (anyone with Wireshark can see any frames)

Question 4

What are benefits of using separate LANs over a single large LAN?

Answer 4

• Additional privacy and security

Question 5

How is it possible to create multiple VLANs on a single switch?

Answer 5

• Switches contain software forwarding already
• Identification by port and MAC address

Question 6

What are some distributed algorithms that run in data centers?

Answer 6

• Spark
• Hadoop

Question 7

What are some common data center architectures?

Answer 7

• Hierarchical Structure
• Interconnection Structure

Question 8

What is a TOR switch?

Answer 8

Top of Rack switch - top of the rack of servers in a data center

Question 9

What are the various media that can be used at the physical layer?

Answer 9

• Co-axial cable
• Twisted pair (phone cables)
• Fiber
• Radio (WiFi, Bluetooth, Cellular, Satellite)