APIPA - Automatic Private IP Addressing - Networking Computer Tips

If you work with PCs for a living or even do your own PC repair and configuration at home you may have heard of a term called APIPA or Automatic Private IP Addressing. If you are known with networks you know that PCs need an IP address to converse with each other. This is how your network in office works and also how internet works. An IP address looks something like 192.168.1.100 and will change based on network configuration. Every PC on network has to have a unique IP address to converse.

When a PC does not have an IP address then it won’t be able to do things like log into a domain, print to network printers or obtain files off of a file server. PCs are assigned IP addresses manually or automatically. PCs that obtain their IP addresses automatically want a source to give those addresses. Generally this comes in form of a DHCP server which has important function of giving IP addresses to network clients. For many home users you generally obtain your IP address from your ISP for dialup and from your DSL/Cable modem for broadband internet connections. If you have a DSL/Cable router then it probably gives your PC’s IP address. These IP addresses are leased to PC for a set amount of time and then want to be renewed or else they will end.

PC will be place to either static or dynamic IP address in its configuration. If its place to obtain IP address automatically and there is no DHCP server on network that can provide it an IP address then it will provide itself an APIPA address. This will generally be in form of 169.254.x.x where x can be a range of various numbers. The reason of an APIPA address is that when PCs lease of its IP address ends then it will have at least some kind of address that can be utilized for network communication. PC will only be able to converse with other PCs that have a 169.254.x.x address which they will get when their lease ends. If other devices like servers and printers have static IP address then APIPA client will not be able to converse with them as they will be on a various IP subnet.

When you are solving network or internet connectivity problems it is best idea to test your IP settings and ensure that you have a valid IP address. If you notice an APIPA address then you knows to begin looking at DHCP source when it comes to troubleshooting.