If you are reading this now, a crazed zombie has just entered the building and can smell your brain. It’s hungry. You have 30 seconds to save your life. Remember to double tap.
Take two, if you are reading this, you have at minimum two Internet Protocol (IP) addresses. You have the one your local network uses to identify you, typically somewhere within these ranges:
10.0.0.0 10.255.255.255
172.16.0.0 172.31.255.255
192.168.0.0 - 192.168.255.255
and you have a public IP so the stuff you ask for and send to the Internet can find its way without getting lost. Even if it’s just you plugged into a DSL bridge or cable modem, you have at minimum two.
Static IP
You can simply tell your computer (the word is synonymous with device because a pad or smartphone is a kind of computer) what your local IP is. If you do this to two devices that are connected and the IPs are in the same range, they can see and talk to each other. You haz a network.
If you are connected to a server either locally or over the Internet, you can also request a static IP. You would do this because you need it to create an encrypted tunnel for data between you and another server, called Virtual Private Networking (VPN). VPNs these days are pretty hard to crack. Nothing, dear reader is unhackable. Some things are are just insanely difficult to hack, which is another way to say reasonably secure.
A static IP is generally not preferred on the Internet for routine browsing. It’s not efficient for the server that’s giving you access to the web and it’s an stationary (unchanging) target for hacking.
Dynamic IP
Your computer sends a request for an IP to a DHCP server. By server I mean any device including a router that assigns addresses. The device has a range of IPs to give. The range is restricted so no two devices have the same IP (you are distinct so your data traffic doesn’t get confused with another device), you are able to navigate, and the server and network doesn’t get overloaded.
If the server validates your request, it leases (assigns) you an IP. The word lease is used because the address expires: it’s no longer valid after a period of time. When the lease expires, the server re-authenticates and issues a new lease. This is a highly efficient way to keep traffic moving because an expired IP can be given to any computer (or gizmo) that needs it.
What needs an IP? Anything you want to send or receive data from over Internet Protocol: printers, scanners, servers, other computers, all things Internets. The broadcast, lease, release, re-assign thing goes on all the time without us knowing about it. Unless it doesn’t work for some reason and we know about it the same way we know a cell phone failed to negotiate a new connection to a different tower: the signal goes dead. The device still works and the thing it was connected to still works, but there’s no way for them to talk.
If you have Windoze, have no connection, and your IP is 169.254.x.x - that’s because your authentication failed and Windoze gave you that IP by default. Micro$oft calls this a feature because it “makes configuring and supporting a small Local Area Network (LAN) running TCP/IP less difficult.” Unless of course that IP is out of range in your network, in which case you might as well have your computer plugged into a toaster. At least you’ll get a nice English muffin.
The Number Crunch
It’s no secret that since networking protocols were first operational, the goal has always been to get everyone a unique address - so there needs to be more addresses available than the peak demand for them or we would get the equivalent of “Sorry your Interwebz cannot be completed as dialed. Please hang up and try the Interwebz when fewer losers are playing Warcraft.” Not that there are any losers playing Warcraft.
It’s also no secret that Internet Service Providers (ISP) and content providers oversell their ability to deliver because not every customer places demands on its corner of the t00bs simultaneously. When they do, entire chunks of the Internet can and do crash. They hate to admit it’s a capacity problem, which retailer Target recently did when some fancy clothes went on sale and so many people tried to buy them, the servers choked (too many simultaneous connections) and took the store offline.
Google and Apple and Micro$oft and others sell cloud computing, which is a fancy name for trust us to run your programs and store your data. Access it from anywhere. Ultimate convenience. Unless you can’t get connected to the Internet because the wind knocked down a tree three miles away and took out the pole carrying the wire your Internet connection uses. One of the problem with clouds: they are at the mercy of wind.
And traffic. DHCP handles this rather well usually. One of the problems they have is the now extremely common “always on” Internet connection - because you need a 24/7 lease. Some ISPs solve this by not actually being always on, just quick at reconnecting you so it feels like it (many wireless providers) or reducing server load for lease and release by extending the lease time or just giving you the same IP back every time. Which means in essence they know you’re authenticated as their customer, but out in the wild west town of the Internet, you have effectively been given a static IP. Not as dynamic as advertised, but not the end of the world. If you stand on the street corner without moving in a dangerous neighborhood where people use guns, you’re easier to hit. Doesn’t mean you wouldn’t get hit changing corners or running between them. DHCP wasn’t designed as a security feature, it was designed as a server efficiency feature.
Obsessively seeking a new IP lease is a way some folks try to cover their tracks. It’s a dangerous game to play because server and firewall logs record those IPs - and unless you understand the intricacies of IPv4 and IPv6, you may be leaving a trail of Internet breadcrumbs to your computer no matter how many IPs you use.
What To Do
If you have a stable zippy connection, don’t fix what isn’t broke. Just be sure you take reasonable precautions to protect your stuff with firewall, antivirus, and proper configuration of your operating system. With a cable or DSL bridge, it probably doesn’t hurt in many instances to powercycle that thing at least once every week or two. Gets the flash drive cobwebs out and might get you a fresh IP. Don’t be surprised if it doesn’t.
ISPs tend to charge more for guaranteed static IPs because they assume (based on experience) that if you want one of those, you’re probably a bandwidth pig using it to work on a remote server over VPN.
Your IP isn’t everything in your address, it’s just a small part of it. There aren’t enough addresses in the world to accommodate all the devices trying to get a lease, so within certain segments of the Internet, other data is included to allow multiple users to use a single IP. Most Internet content servers can host multiple smaller web sites and they typically use one shared IP to do that.