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IP Address Explained: What It Is and How to Quickly Figure out Yours

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If you’ve ever tried troubleshooting your home network or setting up a new router, you must have heard of “IP address” or “IP” for short. This post will explain more—in simple terms—about this type of address, IPv4 vs. IPv6, and help you find out yours at any given time.

Dong’s note: I originally published this post on Feb 15, 2018, and last updated it on May 6, 2019, to add relevant information.

What is an IP address?

IP stands for Internet protocol. IP addresses are how devices identify themselves and talk to one another over the Internet or within a local network.

When you surf a website or browse a network computer, you access a particular IP address. A meaningful domain or computer name—such as or Server—is just a helpful way to mask that address so that we humans can remember it.

By the way, binding an IP address with a meaningful name is the job of a DNS server.

A device can’t get connected if it doesn’t have an IP address, which is uniquely assigned to each network member by a DHCP server (your router). In other words, you can’t have two devices sharing one IP address in the same network and expect them to work correctly, if at all.

To avoid an IP conflict, refrain from manually assigning a static address to a device unless you can keep track of the addresses manually.

Within a local network, generally, the IP address of each member device remains the same for the duration it is on and connected. When you restart the device, its IP address might change unless you choose to reserve the same address for it by binding the IP with the device’s MAC Address.

Asus RT-AX68U 5
In a home network, the router manages all the local IP addresses.

IPv4 vs. IPv6

There are two versions of Internet protocol: IPv4 and IPv6. The former is the most popular and generally the default connotation of an IP address. (You’ll need to call the latter as IPv6 address explicitly). The truth is the popularity of IPv4 is why we need IPv6.

While IPv6 is newer and has been available for a few years, generally, for the most part, we’re still dealing primarily with IPv4 now and long in the future, if not forever.

Internet protocol version four (IPv4)

IPv4 uses a 32-bit pool of addresses. As a result, a typical IPv4 address consists of four groups of three-digit numbers with a dot (.) in between, like this one:

You can omit the leading zeros in each group in an IP address, but each group must retain at least one digit. That said, the address above usually appears as

When you change a number, we have a new address, so mathematically, IPv4 can produce 4,294,967,296—four billion and then some—addresses.

While that seems like a lot, there are about 10 billion people globally, and one of us can have more than one device. IPv4 will inevitably run out of addressing space at some point.

And that brings us to a few terms that seemingly have nothing to do with those numbers mentioned above.

WAN vs. LAN vs. NAT

To conserve the addresses, IPv4 is available at two levels: Wide Area Network (WAN) and Local Area Network (LAN).

At the WAN (or Internet) level, the address is always unique at any given time. Generally, each website has a WAN IP address. At your home, your router (or gateway) has your WAN IP—the one you found out at the beginning of this post.

The router then creates a sub-level LAN network with a different set of local (or private) IP addresses for other devices, such as computers or tablets.

Effectively, this allows multiple devices to access the Internet via a single WAN (or public) IP address instead of each having a WAN IP of its own. The router does that via network address translation or NAT.

DHCP, IP pool, and lease time

In your home, other than the router, which gets the public IP address, the rest of the devices use LAN IP addresses that are unique only within the home network.

These local addresses are given out by a local Dynamic Host Configuration Protocol (DHCP) server. All routers come with a simple version of this server built-in, which is enough for most home networks. (A large network might have a dedicated computer as its advanced DHCP server.)

You can configure your IPv4 address pool using your router's interface.
You can configure your network’s DHCP server, the IPv4 address pool, and the lease time using your router’s interface.

This server creates an IP subnetwork separate from the public WAN network and distributes addresses to all devices connected to the router. The number of addresses, called the IP pool, determines how many devices can be in the same local network at a time. Generally, by the default configuration, a home router can host 253 devices.

When a device connects to a network, it gets a unique local IP address and can hold that address for a fixed amount of time, called the “lease time.” When the lease time expires, its IP address will be reassigned, and it might remain the same or not.

Lease time is generally measured in seconds, and the default number is 86400, which is equal to one day. When a device disconnects, the IP might still be held for it until the lease time expires.

IPv4 will be relevant for a long time

Thanks to the NAT function, you can have two routers with the same local IP subnetwork at two different locations, such as a home and an office. That is possible because the two are “shielded” behind each home’s router’s unique WAN IP address.

This shielding also has another bonus. Devices connected to a router are behind a layer of protection from the outside world. Depending on the router in use and how you configure it, you can keep the entire network safe from identity thieves and other online threats.

The use of NAT is so effective that I believe IPv4’s address pool will suffice for a very long time in the future. (Effectively, NAT allows a large group of people to share a single unique WAN IP instead of each having to have one of their own.)

That’s not to mention many existing IPv4-only devices will last ages more and need to be supported.

So, IPv4 is not going away anytime soon, if at all. In any case, you can always choose to use it within your local network. But we still need something more robust, and that’s the slot IPv6 fills.

Internet protocol version six (IPv6)

IPv6 uses a much larger 128-bit pool of addresses. A typical IPv6 address includes 8 groups of four characters (numbers or letters), divided by colons (:) and looks like this: 2001:0cd8:85e6:0000:0000:8e2c:0450:8733 or 2001:cd8:85e6:0:0:8e2c:450:8733 (leading zeros can be omitted).

While still finite, the total number of IPv6 addresses is exponentially higher than IPv4’s.

Specially, we get the following total of IPv6 addresses:


(That’s 340 trillion trillion trillion and then a couple of hundreds of trillion trillion more.)

At this level, it’s safe to say we’ll never run out of addressing space. That’s great, but it can also bring about some privacy concerns. IPv6 means there’s no need to conserve addresses anymore.

IPv6 and privacy concerns

Among other things, the IPv6 address assigned to each device at any given time can now be unique globally—universally, in fact. In other words, IPv6 addresses are generally always the WAN addresses.

Consequently, when your computer connects to the Internet using IPv6, it’s exposed to the outside world. Thus, folks on the other end—like the website you visit—can trace back directly to it instead of the router, as in the case of IPv4.

As a result, they can potentially tie certain online activities to a specific user. It’s not that easy, and there are ways to minimize the risks—there’s no need to get all worried—but still, the unique IP can imply a lot of things.

Currently, all home networks still use IPv4, with some also using IPv6 alongside. Most home routers support IPv6, but few service providers, if at all, use this new protocol exclusively.

You can usually choose to disable IPv6 at the router level or an individual device. And you should do that—which causes IPv6 to stop at your router—if you don’t want to deal with the new protocol or have privacy concerns.

How to find out your local IP addresses

Again, a local IP address belongs to a device within your home network, and we’re talking mainly about IPv4 here. By the way, you generally can change the scheme of your local IPs via your router’s interface.

The ipconfig /all command reveals a lot of information about your network.
The ipconfig /all command reveals a lot of information about your network.

How to find out the IP address of a Windows computer

  1. Click on the Start button, type in cmd then press Enter. The Command Prompt will appear.
  2. Type in ipconfig or ipconfig /all then press Enter. (The latter command reveals more information.)

Now, you will see your computer’s local IP address (both IPv4 and IPv6) and your router’s default gateway address. By the way, if you use the ipconfig /all command, you’ll also see the MAC address (shown as the Physical Address).

Pro tip: Opening the Gateway IP address in a browser (like Chrome) will take you to your router’s web interface (most routers have one). The interface can, among other things, be used to change your network’s IP settings and find out the IP address of all connected clients in a network—more blow.

How to find out the IP address of a Mac computer

For Wi-Fi users:

Click on the Wi-Fi icon (top right) while holding down the Option key. You will see a menu with loads of information about the connection, including the IP addresses of your computer and the router.

IP Address on a Mac
With an Option + Click on a Mac, you can quickly view a lot of information about your Wi-Fi connection, including your IP address.

If your Mac connects via a network cable, then do this:

  1. Click on the Apple icon (top left) and then System Preferences.
  2. Find the Network icon and click on it.
  3. Click on the current connection. Here you’ll find the information you need.

How to find out the IP address of any device in a local network

This part applies to a network with multiple connected devices, and you want to find out the IP address of any particular one among them.

This trick is helpful when you need to configure a device—be it a printer, an access point, or an IP camera—using the computer you are using. It’s also useful when you want to know the IP of another computer in the network that you’re not using.

An example of a connected client list within a router's web interface. Note the MAC and IP addresses.
Here’s an example of a connected client list within a router’s web interface. Note the MAC and IP addresses.

To figure out the IP address of another device in the network, you need to have access to the network’s DHCP server—in most cases, that’s the router. Here are the steps:

  1. Log in to the router’s web interface using its IP address—see the Pro-tip above.
  2. Navigate to the LAN section of the interface and then the DHCP server section. Some routers have a network map that shows the connected clients and their IP addresses.
  3. Here, you’ll see the list of connected clients. Most of the time, they have their names listed. If not, you can always find out which one is which by their MAC address.

Knowing a device’s IP means you can access it via the address. If the device has a web interface, most printers and Wi-Fi access points do, and you can open this interface via its IP address.

Extra: When and how to reserve an IP address for a device

Reserving an IP address (or a DHCP address) binds a device’s MAC address with an IP address. From then on, the router will keep that particular IP for that specific MAC address. So, every time the device connects to the network, it will get that same IP address.

This setting is helpful in situations where you don’t want the device’s IP to change. Examples are when you use a network printer, a network security camera, or a server of any kind. When the IP changes, the application you’ve set up with the particular device might not work anymore. It’s always so in the case of port-forwarding.

While you don’t need to reserve the IP for all connected clients, it doesn’t hurt if you do so, either, as long as you remember to remove the reservation when a client is no longer part of the network.

Note that generally, a router can only keep track of so many reserved IP addresses—the number ranges from 8 to 128. If you want more devices to have a static local IP address, manual IP assignment is the way to go. In this case, in a standard setup, you can have all 253 local devices with their static IP.

IP Reservation
On Linksys router, you can easily reserve an IP address on the Network map.

The steps to make an IP reservation vary from one web interface to another, but you can almost always do that at the place where you can view the list of connected clients or the network map.

Most home routers—those from Asus, TP-Link, D-Link, Netgear, and Synology—allow you to do that via a click. With others, you might have to enter the MAC address and the IP address manually.

Final notes on the WAN IP address

The WAN IP address is the unique address that represents your entire home network to the Internet. For this reason, it’s known as your public IP address. You can instantly look up your  WAN IP address at the top of this post. You can also Google “What’s my IP.”

Generally, your service provider assigns the WAN IP address to your home router (via the modem), and you can’t change it.

Note that this public address tends to change occasionally unless you pay for an expensive static IP.

That said, you can’t just write it down and expect to be able to dial home when you want. To keep tabs on your WAN IP when you’re away from home, you need to use a Dynamic DNS service, and that deserves a different post entirely.

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15 thoughts on “IP Address Explained: What It Is and How to Quickly Figure out Yours”

  1. Dong, can you clarify something?

    I have FTTP and am in the process of switching broadband providers (my ISP is shutting down) and am confused by the “features” some of the other providers are listing online. As far as I know I currently have a dynamic IP.

    Some of the ISPs now make it a point to list amongst their various “features” (alongside the speed) points like “Static IPv4 Address” or “Static IPv6 Address”. As far as I know, ISPs who don’t list that simply give customers a dynamic IP. But it seems like a lot of them now seem to be offering the “static IP” as default.

    I am not running a website, sales business or servers which from what I understand are one of the reasons one might need a static IP. Generally speaking I prefer privacy. I’m going to buy an Asus router of my own as well as I don’t want to have to sign in to a vendor to manage my network (we’ve just wired our home).

    But I am slightly confused if I sign up with an ISP who is giving a “static IP” by default, whether that means potential hostile actors or third parties can trace/monitor one’s activity or even hack more easily?

    Should one therefore be adamantly looking for an ISP who does NOT offer a service with a static IP?

    • Most, if not all, ISPs offer static IP addresses. I’m not aware of any that doesn’t. It’s a valuable asset for those to run certain services, such as a website via their own server as you mentioned. Without a static WAN IP, you’d need Dynamic DNS if you want to have any applications that require to call back home which is still not as reliable as a static IP. But for most homes, and many businesses in fact, a static IP is not necessary.

      • Thanks Dong, but what I’m asking is, is going for an ISP that specifically states you will be given a “Static IP” going to create more problems than its worth? Versus an ISP that simply gives customers a Dynamic IP.

        Some ISPs list they give you a Static IP as an included feature. Whereas others who don’t list it, seem to simply be offering a Dynamic IP when you look into their FAQs.

        I was concerned that if I move to a Broadband provider who uses a Static IP, that it might mean we’re suddenly more susceptible to tracking, hackers or troublemakers if our public facing IP address never changes.

        • You’re not more susceptible, James. But if you don’t have the need for a static IP, there’s no point in paying for one. If you get one for free, that’s a bonus, and in most cases, you don’t need to use it and set up the WAN connection with a dynamic one (the default option).

  2. I am getting both IPv4 and IPv6 addresses from my home router.
    When I configure DHCP IP Reservation, do I reserve both IPV4 and IPv6 addresses for my client device?

    Thank you

    • That depends, Roberto. But generally, IP reservation, Dynamic DNS, and port forwarding are applicable only to IP4. Also, you should disable the use of IPv6 in your local network — there’s no use for it and it only makes your device more susceptible to privacy risks.

  3. Hi Dong.
    I very much want to be able to use my AX-92U’s USB port to access the connected SSD drive from outside OTG, (i.e., as a NAS). When I try to set it up with my choice domain ( I repeatedly get an error,
    ‘invalid IP address’.
    Between my NTT (FTTH) router ( to the WWW and my ASUS AX92U ( sits my ISP’s (SoftBank JP) router which assigns the IPv4 address to access WWW.

    WWW<=(ftth) NTT ( (LAN) <= (WAN) Softbank JP (LAN) <= (WAN) RT-AX92U ( (I will also change to a lucky number :-))

    (I wish I could attach a photo or diagram as a picture says a 1,000 words)

    Per your article here and other 'WiFi Router USB: The 1st Solid NAS option' port for NAS function, it seems I am missing something or not understanding something properly. 'Invalid IP Address' means I can not use ASUS' DDNS' service at all? I would think not. Thanks much. Jerry. Tokyo.

  4. Thanks for having a place where I can find as much info as I need for any situation. I would start with one article and I would find myself exploring even more info.

    If I’m reading the things correctly (pretty new at all the info about setting up a mesh system down the road (from a pitiful extender), does the Gateway’s IP address represent the Gateway’s router, which is their WAN IP? Is it this address that I need to make sure the new router does not have the same if I’m going to set up the new router in Bridge Mode? Do I change this IP before I enable Bridge Mode?

    • Generally, Laura, a router’s (or a gateway)’s default IP address, the one you can use to access its web user interface, is called the “Default Gateway” address. (NOT “Gateway’s IP address” — note the apostrophe). The word “Gateway” in this case has NOTHING to do with what a gateway is.

      And no, that’s NOT its WAN IP, which changes. But yes, from outside (the WAN side), you can use its WAN IP to access its interface, too, if you turned on the remote management — more here.

      Again, when talking about a router, keep this in mind:

      1. Gateway IP address (or default IP address) is referred to the IP address of the router itself, which is unique locally. It represents the fact the router is the HOST of a network.
      2. WAN IP address: It’s the IP address the router gets from the ISP (or any Internet source including another router). It represents the fact the router is a MEMBER of a larger network outside of the one it hosts — the world wide web.

      That said, I’d recommend you read this post (and others) again and get the definitions down. You’re getting close. Using names arbitrarily will make it impossible for anyone to know what you’re talking about.

      • How can i cloan a router and modem my girlfriend lives to change the Wi-Fi password on me yes I have 100 foot Ethernet cable lol still not log enough awhile back our 5g stop working and she only uses 2 g could i take my old 5g router and Modem they are the same I just stop paying the internet when she moved in so I still have my router and modem is there away to take it out to the garage and hard wire it some how with out knowing the Wi-Fi password she thinks she’s got all the power haha and she does and I have 2 sets one left over from my old internet I’m not even sure I own and 2 that I do . So do internet companies know when your use there equipment to go go gadget around my crazy wonderful girlfriend I just wanna game Maybe 10 percent more lol so those are my questions how to clone the 5g router And they already know what you’re gonna say but then does sm alone she would know we’re talking stage five level Klinger wouldn’t have it any other way so she won’t notice it’s moved even tho it hasn’t spit out a signal in months get take the ip and Mac loaded up into mine and access the internet wirelessly but still with a Ethernet cable she may have wit but I know I can put smart her on this one know more hijacking’s of the Wi-Fi password to get what you want lol there is wills so therefore we there is way sag com router and arris modem

  5. Hi Dong

    Thanks for the explanation. Its very usefull. I have a question regarding the IP address for use in home networks. Did you recommend to use the standard 192.168.1.xx or it is recommend for security to start with different range that the ones that comes in a router. Is there any issue, Let me know your comments and suggest.


    • Sure, Hector. Technically, it doesn’t matter, but personally I’d change 1 into something else, like your lucky number — mine is 13 :). That way, you can avoid conflicts in some cases, and always know for sure if a device get the IP from your router’s pool.

  6. I thought it was interesting when you explained that an IP address is how a device can identify itself over the internet. If I remember correctly, someone recently told me that people can buy and sell IP addresses if they want to get a specific one. It would be interesting to learn more about how this process of buying and selling works.

    • Among other things, it works by not spending time and spamming the audience of a website with the business’s link, Henry.


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