The Physical Network

Question 1

What are the characteristics of a physical network that we care about when designing web applications?

Answer 1

1. latency: thetimeit takes for some data to get from one point in a network to another point in a network. (in ms)
2. Bandwidth: theamountof data that can be sent in a particular unit of time (typically, a second).

Question 2

What are the elements of latency?

Answer 2

1. Propagation delay
2. Transmission delay
3. Processing delay
4. Queuing delay

Question 3

What is Propagation delay?

Answer 3

the amount of time it takes for a message to travel from the sender to the receiver

Question 4

What is transmission delay?

Answer 4

Transmission delay is the amount of time it takes to push the data onto the different systems it travels on (different routers and cable networks).

Question 5

What is Processing delay?

Answer 5

The amount of time it takes to process the data between links.

Question 6

What is queuing delay?

Answer 6

The amount of time the data is waiting in the queue to be processed if there is more data than a particular router can handle.

Question 7

What is last-mile latency?

Answer 7

Because there are shorter links at the edge of the network, a lot of the delays described above can take place within the parts of the network which are closest to the end points. relates to the delays involved in getting the network signal from your ISP’s network to your home or office network.

Question 8

What is Round-trip Time (RTT)?

Answer 8

the length of time for a signal to be sent, added to the length of time for an acknowledgement or response to be received.

Question 9

What is a Bandwidth Bottleneck?

Answer 9

A point at which bandwidth changes from relatively high to relatively low.