MAC address is of :
48 bits
Understanding MAC Addresses and Their Size
A MAC address, which stands for Media Access Control address, is a unique identifier assigned to a network interface controller (NIC) for use as a network address in communications within a network segment. MAC addresses are used in various network technologies, including Ethernet and Wi-Fi.
Think of a MAC address like the physical serial number of your network card. It's usually hardwired into the device by the manufacturer.
The Size of a MAC Address in Bits
The standard length for a MAC address, as defined by the IEEE 802 standards, is 48 bits.
These 48 bits provide a very large number of possible unique addresses, which is necessary because every network-enabled device in the world needs a unique identifier.
Representation of a 48-bit MAC Address
While a MAC address is fundamentally a 48-bit binary number, it is typically represented in a more human-readable format using hexadecimal digits.
Since 4 bits make up a single hexadecimal digit (because \(2^4 = 16\)), a 48-bit address can be represented by 12 hexadecimal digits (\(48 \text{ bits} / 4 \text{ bits/hex digit} = 12 \text{ hex digits}\)).
These 12 hexadecimal digits are often grouped and separated by colons, hyphens, or dots. Common formats include:
MM:MM:MM:SS:SS:SS(using colons)MM-MM-MM-SS-SS-SS(using hyphens)MMMM.MMSS.SSSS(using dots)
In these representations, 'M' often represents digits from the manufacturer's assigned part, and 'S' represents digits from the unique serial number part.
Structure of the 48-bit MAC Address
The 48 bits of a MAC address are typically divided into two main parts:
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Organizationally Unique Identifier (OUI): The first 24 bits are assigned to the manufacturer by the IEEE Registration Authority. This part identifies the organization that manufactured the network hardware.
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Controller Specific Identifier: The last 24 bits are assigned by the manufacturer. This part is unique to the specific network interface controller produced by that manufacturer.
This two-part structure ensures that manufacturers can assign unique addresses to their devices without needing to coordinate with other manufacturers for every single address.
Comparing Options
Let's look at the given options based on our understanding of MAC address size:
- 24 bits: This is the size of the OUI part, but not the full MAC address.
- 36 bits: This is not the standard size for a MAC address.
- 48 bits: This is the standard size for a MAC address.
- 42 bits: This is not the standard size for a MAC address.
Based on the standard IEEE 802 definition, a MAC address is 48 bits long.
| Aspect | Description |
|---|---|
| Full Name | Media Access Control Address |
| Purpose | Unique identifier for network interface controllers (NICs) on a network segment. |
| Standard Size | 48 bits |
| Common Representation | 12 hexadecimal digits (e.g., XX:XX:XX:XX:XX:XX) |
| Structure | First 24 bits: OUI (Manufacturer ID) Last 24 bits: Controller Specific Identifier |
Revision Table: MAC Address Key Facts
| Feature | Detail |
|---|---|
| What is it? | Hardware address of a network interface. |
| How long? | 48 bits |
| How represented? | Hexadecimal (12 digits), e.g., 00:A0:C9:14:C8:29 |
| Parts | OUI (24 bits) + Device Identifier (24 bits) |
Additional Information: MAC vs. IP Addresses
It's helpful to distinguish between MAC addresses and IP addresses, as they serve different roles in networking:
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MAC Address: Operates at Layer 2 (Data Link Layer) of the OSI model. It is used for local communication within a single network segment (like your home network). It identifies the physical device.
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IP Address: Operates at Layer 3 (Network Layer). It is used for routing data across different networks (like the internet). It identifies a connection to a network, and can change (e.g., when you connect to a different network or use DHCP).
A MAC address is a hardware address, while an IP address is typically a software address.
Important Questions from Miscellaneous
A stone is thrown horizontally from the top of a 20 m high building with a speed of 12 m/s. It hits the ground at a distance R from the building. Taking g = 10 m/s2 and neglecting air resistance will give :
A sphere of volume V is made of a material with lower density than water. While on Earth, it floats on water with its volume f1V (f1 < 1) submerged. On the other hand, on a spaceship accelerating with acceleration a < g (g is the acceleration due to gravity on Earth) in outer space, its submerged volume in water is f2V. Then:
A railway wagon (open at the top) of mass M1 is moving with speed v1 along a straight track. As a result of rain, after some time it gets partially filled with water so that the mass of the wagon becomes M2 and speed becomes v2. Taking the rain to be falling vertically and the water stationery inside the wagon, the relation between the two speeds v1 and v2 is :
Consider the following statements:
1. Distance between the longitudes becomes zero on North Pole and South Pole.
2. Distance between the longitudes is maximum on the Equator.
3. Number of longitudes is more than number of latitudes.
Which of the statements given above is/are correct?
One block of 2⋅0 kg mass is placed on top of another block of 3⋅0 kg mass. The coefficient of static friction between the two blocks is 0⋅2. The bottom block is pulled with a horizontal force F such that both the blocks move together without slipping. Taking acceleration due to gravity as 10 m/s2, the maximum value of the frictional force is :
