Suggest an editImprove this articleRefine the answer for “What parts does an IPv4 address consist of?”. Your changes go to moderation before they’re published.Approval requiredContentWhat you’re changing🇺🇸EN🇺🇦UAPreviewTitle (EN)Short answer (EN)**An IPv4 address** is divided into two logical parts: the network part and the host part. These parts are defined by the subnet mask or a CIDR prefix (for example, /24). **Key point:** the network part is the same for every device in a subnet, while the host part is different for each device.Shown above the full answer for quick recall.Answer (EN)Image**An IPv4 address is divided into two logical parts:** 1. **Network Part** 2. **Host Part** These parts are defined by the **subnet mask** or a CIDR prefix (for example, /24). --- ## **1. Network Part** The network part determines **which network the address belongs to**. - The same for all devices within one subnet. - Used by routers to determine the path. - Allows grouping devices into one network. Examples of the network part: - In the **192.168.1.0/24** network: the network part is *192.168.1*. - In the **10.5.0.0/16** network: the network part is *10.5*. - In the **172.16.32.0/20** network: the network part is *172.16.32.* (plus part of the next octet). --- ## **2. Host Part** The host part identifies **the specific device within the network**. - This part is **different** for every host in the network. - Defines the range of possible IP addresses within the subnet. - Used only within the network itself (routers do not take it into account when choosing a route). Examples of the host part: - In the **192.168.1.0/24** network: numbers from *1 to 254*. - In the **10.5.0.0/16** network: numbers from *0.0.1 to 255.255*. - In the **172.16.32.0/20** network: the last 12 bits of the address. --- ## Important special addresses within a subnet Every subnet has 2 reserved addresses: #### **1. Network address** Host part = all 0. Example: **192.168.1.0** in a /24 network. #### **2. Broadcast address** Host part = all 1. Example: **192.168.1.255** in a /24 network. They are not assigned to devices. --- ## Example: breaking down a full IPv4 address Suppose the address is: ``` 192.168.10.25/24 ``` The /24 mask means: - the first **24 bits**: the network part - the last **8 bits**: the host part Breakdown: - **Network:** 192.168.10.0 - **Host part:** .25 - **Broadcast:** 192.168.10.255 - **Host range:** .1 → .254 --- ## Why is IPv4 split into two parts? So that routers can: - quickly determine the direction a packet should travel; - group hosts into subnets; - minimize routing tables. This is the foundation of routing and network operation. --- ## **Ready answer for an interview** > **An IPv4 address is split into two parts: network and host.** > **The network part defines the subnet itself and is the same for all devices in it.** > **The host part identifies the specific node within the subnet.** > **The split is done using the subnet mask (for example, /24).** --- ## Cheat sheet (5 seconds before the interview) - IPv4 address = **Network + Host**. - Where the boundary lies is determined by the **mask**. - Network: common for the subnet. - Host: unique for each device. - Reserved: **network address** and **broadcast**.For the reviewerNote to the moderator (optional)Visible only to the moderator. Helps review go faster.