IP Classes and MAC address explained
### IP Address Classes
An IP (Internet Protocol) address is a unique identifier assigned to each device connected to a network that uses the Internet Protocol for communication. There are two versions of IP addresses: IPv4 and IPv6. Here, we’ll focus on IPv4 addresses and their classes.
#### IPv4 Address Classes
IPv4 addresses are 32-bit numbers, usually represented in dotted decimal format (e.g., 192.168.0.1). The IPv4 address space is divided into five classes (A, B, C, D, and E) based on the leading bits of the address. The class determines the network and host portions of the address, affecting the number of available networks and hosts per network.
1. **Class A**
– **Range:** 1.0.0.0 to 126.0.0.0
– **Default Subnet Mask:** 255.0.0.0
– **First Octet Range:** 1-126
– **Leading Bits:** 0
– **Purpose:** Designed for very large networks with many devices.
2. **Class B**
– **Range:** 128.0.0.0 to 191.255.0.0
– **Default Subnet Mask:** 255.255.0.0
– **First Octet Range:** 128-191
– **Leading Bits:** 10
– **Purpose:** Designed for medium-sized networks.
3. **Class C**
– **Range:** 192.0.0.0 to 223.255.255.0
– **Default Subnet Mask:** 255.255.255.0
– **First Octet Range:** 192-223
– **Leading Bits:** 110
– **Purpose:** Designed for small networks.
4. **Class D**
– **Range:** 224.0.0.0 to 239.255.255.255
– **First Octet Range:** 224-239
– **Leading Bits:** 1110
– **Purpose:** Reserved for multicast groups (used for one-to-many communication).
5. **Class E**
– **Range:** 240.0.0.0 to 255.255.255.255
– **First Octet Range:** 240-255
– **Leading Bits:** 1111
– **Purpose:** Reserved for experimental purposes and future use.
### MAC Address
A MAC (Media Access Control) address is a hardware identifier that uniquely identifies each device on a network. Unlike IP addresses, which can change, MAC addresses are assigned by the manufacturer and are usually fixed.
#### MAC Address Structure
– **Length:** 48 bits (6 bytes)
– **Representation:** Usually written in hexadecimal format, separated by colons (e.g., 00:1A:2B:3C:4D:5E) or hyphens (e.g., 00-1A-2B-3C-4D-5E).
#### MAC Address Components
1. **OUI (Organizationally Unique Identifier):**
– The first 24 bits (3 bytes) of the MAC address.
– Identifies the manufacturer of the network device.
2. **NIC (Network Interface Controller) Specific:**
– The last 24 bits (3 bytes) of the MAC address.
– Uniquely identifies the specific device within the manufacturer’s range.
#### Purpose of MAC Address
– **Local Identification:** MAC addresses operate at the data link layer (Layer 2) of the OSI model and are used to uniquely identify devices within a local network segment.
– **Frame Delivery:** MAC addresses are essential for the delivery of data frames within the same network segment.
– **Security:** MAC addresses can be used for network security purposes, such as MAC filtering on routers and switches to allow or deny devices based on their MAC addresses.
### Differences Between IP Address and MAC Address
– **Layer:** IP addresses operate at the network layer (Layer 3) of the OSI model, while MAC addresses operate at the data link layer (Layer 2).
– **Permanence:** IP addresses can change (e.g., when moving between networks), whereas MAC addresses are usually permanent and tied to the hardware.
– **Scope:** IP addresses are used for routing data between different networks, while MAC addresses are used for local network communication.
Understanding IP address classes and MAC addresses is fundamental for networking, as they play crucial roles in network design, communication, and security.
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