Suggest an editImprove this articleRefine the answer for “What are private IP addresses?”. Your changes go to moderation before they’re published.Approval requiredContentWhat you’re changing🇺🇸EN🇺🇦UAPreviewTitle (EN)Short answer (EN)**Private IP addresses** are IP addresses intended for use inside local networks that are not routed directly to the Internet. **Key point:** devices with private IPs reach the Internet through NAT, which substitutes the private address for a public one.Shown above the full answer for quick recall.Answer (EN)Image**Private IP addresses** are **IP addresses intended for use inside local networks** that **are not routed directly to the Internet**. Short and clear: **private IP addresses are used inside a network and are not visible on the Internet**. --- ## Why private IP addresses are needed Private IP addresses allow you to: - build local networks (at home, in an office, in a data center) - use the same IP addresses in different networks - save public IPv4 addresses - isolate an internal network from the Internet --- ## Ranges of private IP addresses (IPv4) The standard (RFC 1918) defines three ranges: ### 1. **10.0.0.0 - 10.255.255.255** ``` 10.0.0.0/8 ``` - a very large range - often used in large networks --- ### 2. **172.16.0.0 - 172.31.255.255** ``` 172.16.0.0/12 ``` - a medium-sized range --- ### 3. **192.168.0.0 - 192.168.255.255** ``` 192.168.0.0/16 ``` - the most popular - used in home and office networks --- ## What is important to understand - private IP addresses: - **are not globally unique** - can repeat in different networks - routers on the Internet: - **do not accept** packets with private IPs - such packets are dropped --- ## How private IPs reach the Internet **NAT (Network Address Translation)** is used to access the Internet: - inside the network: a private IP - outside: a public IP - the router substitutes the addresses That is exactly why: - dozens of devices can access the Internet - using **a single public IP address** --- ## Private addresses and IPv6 Important for an interview - IPv6 also has local addresses - but the concept is different - NAT in IPv6 **is not mandatory** --- ## In short, for an interview > **Private IP addresses** are ranges of IP addresses intended for use inside local networks that are not routed to the Internet and usually reach outside through NAT.For the reviewerNote to the moderator (optional)Visible only to the moderator. Helps review go faster.