Scalability of a network

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Quick Questions

Shade in the A or B circle for each question.

1. Which best describes a scalable network?

A It can never be changed once it is built

B It can grow in users, devices and traffic without a major redesign

2. A school buys a 48-port switch but only uses 30 ports. What does this help with?

A Spare ports make the network faster right away

B Spare ports let new devices be plugged in later

3. Which choice shows planning for growth?

A Choosing a switch with more ports than are needed today

B Buying exactly as many ports as there are devices today

4. A company expects to double its staff in two years. Which network design is more scalable?

A One that can have extra switches and access points added later

B One that must be completely replaced to add more staff

5. What is an upgrade path?

A A way to add capacity later, such as faster links or more switches

B A cable that runs between two buildings

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1scalability		AThe design ignores future growth. When users and traffic increase, the network will need a major redesign.
2spare_ports = 8		BEvery switch port is already in use, so there are no spare ports. A new device would need extra hardware or a redesign.
3Planning for growth: choosing a switch with more ports than are needed today		Cupgrade: 1 Gbps -> 10 Gbps
4An upgrade path: the network can move to faster links later without replacing everything		Dswitch_ports = devices * 1.5
5switch_ports = devices # all 24 ports used		EThe ability of a network to grow in users, devices and traffic without a major redesign
6design_for = current_users_only		FUnused switch ports kept free so new devices can be plugged in as the network grows

Definitions

scalability

Fill in the Blanks

Complete each line of code by filling in the missing parts.

spare = ports _ used

if spare __ 0: print("Add a switch")

future = devices _ 2

if devices > ports: ports = _____ + 24

for i in _____(5): devices = devices + 1

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A def spare_ports(ports, used)

B return ports - used

C print(spare_ports(24, 18))

Question 2

A if devices <= ports:

B print('Buy another switch')

C else:

D print('Spare ports left')

Question 3

A users = 40

B growth = = 0.25

C future = users * (1 + growth)

D print(future)

Question 4

A users = 50

B rate = 0.2

C for year in range(3):

D users = users * rate

E print(users)

Question 5

A speeds = [1, 10, 40]

B current = speeds(0)

C upgrade = speeds[1]

D print(current, upgrade)

Answer Key

Scalability of a network

Section A: Quick Questions

B — It can grow in users, devices and traffic without a major redesign

B — Spare ports let new devices be plugged in later

A — Choosing a switch with more ports than are needed today

A — One that can have extra switches and access points added later

A — A way to add capacity later, such as faster links or more switches

Section B: Match the Pairs

scalability → The ability of a network to grow in users, devices and traffic without a major redesign

spare_ports = 8 → Unused switch ports kept free so new devices can be plugged in as the network grows

Planning for growth: choosing a switch with more ports than are needed today → switch_ports = devices * 1.5

An upgrade path: the network can move to faster links later without replacing everything → upgrade: 1 Gbps -> 10 Gbps

switch_ports = devices # all 24 ports used → Every switch port is already in use, so there are no spare ports. A new device would need extra hardware or a redesign.

design_for = current_users_only → The design ignores future growth. When users and traffic increase, the network will need a major redesign.

Section C: Definitions

scalability — A scalable network can grow in users, devices and traffic without a major redesign, for example by planning for growth, keeping spare switch ports and having an upgrade path.

Section D: Fill in the Blanks

spare = ports - used

if spare == 0:
    print("Add a switch")

future = devices * 2

if devices > ports:
    ports = ports + 24

for i in range(5):
    devices = devices + 1

Section E: Spot the Error

A — A Python function definition must end with a colon. It should be def spare_ports(ports, used):

A — The switch is full only when devices >= ports. Using <= would say 'Buy another switch' while spare ports still exist. It should be if devices >= ports:

B — Assigning a value to a variable uses a single =. The comparison operator == is wrong here and the line has a syntax error. It should be growth = 0.25

D — Planning for growth means adding growth to the current users, so you multiply by (1 + rate). Multiplying by just rate would shrink the user count. It should be users = users * (1 + rate)

B — List items are accessed with square brackets, not round brackets. Round brackets try to call speeds as a function. It should be current = speeds[0]