About Lesson
IPv4 Address Structure
Describe the structure of an IPv4 address including the network portion, the host portion, and the subnet mask.
Network and Host Portions
- An IPv4 address is a 32-bit hierarchical address that is made up of a network portion and a host portion.
- When determining the network portion versus the host portion, you must look at the 32-bit stream.
- A subnet mask is used to determine the network and host portions.
The Subnet Mask
- To identify the network and host portions of an IPv4 address, the subnet mask is compared to the IPv4 address bit for bit, from left to right.
- The actual process used to identify the network and host portions is called ANDing.
The Prefix Length
- A prefix length is a less cumbersome method used to identify a subnet mask address.
- The prefix length is the number of bits set to 1 in the subnet mask.
- It is written in “slash notation” therefore, count the number of bits in the subnet mask and prepend it with a slash.
| Subnet Mask | 32-bit Address | Prefix Length |
|---|---|---|
| 255.0.0.0 | 11111111.00000000.00000000.00000000 | /8 |
| 255.255.0.0 | 11111111.11111111.00000000.00000000 | /16 |
| 255.255.255.0 | 11111111.11111111.11111111.00000000 | /24 |
| 255.255.255.128 | 11111111.11111111.11111111.10000000 | /25 |
| 255.255.255.192 | 11111111.11111111.11111111.11000000 | /26 |
| 255.255.255.224 | 11111111.11111111.11111111.11100000 | /27 |
| 255.255.255.240 | 11111111.11111111.11111111.11110000 | /28 |
| 255.255.255.248 | 11111111.11111111.11111111.11111000 | /29 |
| 255.255.255.252 | 11111111.11111111.11111111.11111100 | /30 |
Determining the Network: Logical AND
- A logical AND Boolean operation is used in determining the network address.
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- Logical AND is the comparison of two bits where only a 1 AND 1 produces a 1 and any other combination results in a 0.
- 1 AND 1 = 1, 0 AND 1 = 0, 1 AND 0 = 0, 0 AND 0 = 0
- 1 = True and 0 = False
- To identify the network address, the host IPv4 address is logically ANDed, bit by bit, with the subnet mask to identify the network address.
Network, Host, and Broadcast Addresses
Within each network are three types of IP addresses:
- Network address
- Host addresses
- Broadcast address
Other related topics
| Topic Title | Topic Objective |
|---|---|
| IPv4 Address Structure | Describe the structure of an IPv4 address including the network portion, the host portion, and the subnet mask. |
| IPv4 Unicast, Broadcast, and Multicast | Compare the characteristics and uses of the unicast, broadcast, and multicast IPv4 addresses. |
| Types of IPv4 Addresses | Explain public, private, and reserved IPv4 addresses. |
| Network Segmentation | Explain how subnetting segments a network to enable better communication. |
| Subnet an IPv4 Network | Calculate IPv4 subnets for a /24 prefix. |
| VLSM | Variable length subnet mask is a computer networking technique to divide an IP network into subnets with different subnet masks |
Other useful information
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