Manufacturer code and serial code in a MAC address

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Quick Questions

Shade in the A or B circle for each question.

1. In the MAC address 00:1A:2B:3C:4D:5E, which part is the manufacturer code?

A 00:1A:2B (the first three pairs)

B 3C:4D:5E (the last three pairs)

2. In the MAC address 00:1A:2B:3C:4D:5E, which part is the serial code?

A 00:1A:2B (the first three pairs)

B 3C:4D:5E (the last three pairs)

3. Two NICs are made by the same manufacturer. What is true about their MAC addresses?

A They have the same second half

B They have the same first half

4. Why do two NICs from the same manufacturer have different serial codes?

A So that each NIC has a unique MAC address

B So that the manufacturer can be identified

5. A NIC has the MAC address A4:5E:60:11:22:33. Another NIC has A4:5E:60:99:88:77. What does this show?

A Same manufacturer, different serial codes

B Different manufacturers, same serial code

Match the Pairs

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

Left column		Right column
100:1A:2B		ATwo NICs from the same manufacturer share the manufacturer code, but each has a different serial code so that every NIC is unique.
23C:4D:5E		BThe second half of the MAC address 00:1A:2B:3C:4D:5E, which is the serial code that makes this NIC unique
3Two NICs made by the same manufacturer share the same first half but have different second halves		C00:1A:2B is the first half, so it is the manufacturer code, not the serial code. The serial code is the last half, 3C:4D:5E.
4A MAC address is split into two halves of three pairs each: manufacturer code, then serial code		DThe first half of the MAC address 00:1A:2B:3C:4D:5E, which is the manufacturer code
500:1A:2B:3C:4D:5E - the serial code is 00:1A:2B		E00:1A:2B:3C:4D:5E and 00:1A:2B:7F:8A:9B
6Two NICs from the same manufacturer have the same serial code		F00:1A:2B \| 3C:4D:5E

Definitions

00:1A:2B:3C:4D:5E

Fill in the Blanks

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

MAC address: 00:1A:2B:3C:4D:5E Manufacturer code: ________

MAC address: 00:1A:2B:3C:4D:5E Serial code: ________

NIC 1: 00:1A:2B:3C:4D:5E NIC 2 (same maker): ________:7F:80:91

NIC 1: 00:1A:2B:3C:4D:5E NIC 2: 00:1A:2B:7F:80:91 Serial codes are _________ for each NIC

First 3 pairs = manufacturer code Last 3 pairs = ______ code

Spot the Error

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

Question 1

A mac ← "00:1A:2B:3C:4D:5E"

B mac ← "00:1A:2B:3C:4D"

C serial ← "3C:4D:5E"

Question 2

A mac ← "00:1A:2B:3C:4D:5E"

B maker ← "00:1A:2B"

C serial ← "3C:4D:5E"

D OUTPUT "Serial: " + maker

Question 3

A DECLARE mac : INTEGER

B mac ← "00:1A:2B:3C:4D:5E"

C OUTPUT mac

Question 4

A nic1 ← "00:1A:2B:3C:4D:5E"

B nic2 ← "00:1A:2B:7F:80:91"

C sameMaker ← FALSE

D sameSerial ← FALSE

Question 5

A mac ← "00:1A:2B:3C:4D:5E"

B maker ← LEFT(mac, 8)

C serial ← RIGHT(mac, 8)

D OUTPUT "NIC id: " + maker

Answer Key

Manufacturer code and serial code in a MAC address

Section A: Quick Questions

A — 00:1A:2B (the first three pairs)

B — 3C:4D:5E (the last three pairs)

B — They have the same first half

A — So that each NIC has a unique MAC address

A — Same manufacturer, different serial codes

Section B: Match the Pairs

00:1A:2B → The first half of the MAC address 00:1A:2B:3C:4D:5E, which is the manufacturer code

3C:4D:5E → The second half of the MAC address 00:1A:2B:3C:4D:5E, which is the serial code that makes this NIC unique

Two NICs made by the same manufacturer share the same first half but have different second halves → 00:1A:2B:3C:4D:5E and 00:1A:2B:7F:8A:9B

A MAC address is split into two halves of three pairs each: manufacturer code, then serial code → 00:1A:2B | 3C:4D:5E

00:1A:2B:3C:4D:5E - the serial code is 00:1A:2B → 00:1A:2B is the first half, so it is the manufacturer code, not the serial code. The serial code is the last half, 3C:4D:5E.

Two NICs from the same manufacturer have the same serial code → Two NICs from the same manufacturer share the manufacturer code, but each has a different serial code so that every NIC is unique.

Section C: Definitions

00:1A:2B:3C:4D:5E — First 3 pairs (00:1A:2B) are the manufacturer code; last 3 pairs (3C:4D:5E) are the serial code that makes this NIC unique.

Section D: Fill in the Blanks

MAC address: 00:1A:2B:3C:4D:5E
Manufacturer code: 00:1A:2B

MAC address: 00:1A:2B:3C:4D:5E
Serial code: 3C:4D:5E

NIC 1: 00:1A:2B:3C:4D:5E
NIC 2 (same maker): 00:1A:2B:7F:80:91

NIC 1: 00:1A:2B:3C:4D:5E
NIC 2: 00:1A:2B:7F:80:91
Serial codes are different for each NIC

First 3 pairs = manufacturer code
Last 3 pairs = serial code

Section E: Spot the Error

B — A MAC address has six pairs. This one only has five, so the serial code is incomplete. It should be "00:1A:2B:3C:4D:5E".

D — The label says Serial, so it must output the serial variable (the last three pairs), not the manufacturer code. It should be OUTPUT "Serial: " + serial.

A — A MAC address contains colons and hexadecimal letters such as A to F, so it must be stored as text. It should be DECLARE mac : STRING.

C — Both NICs start with 00:1A:2B, so they have the same manufacturer code. sameMaker should be TRUE.

D — The serial code is what makes this NIC unique, because many NICs share a manufacturer code. It should output serial, not maker.