What’s an IP Conflict and How Do You Resolve It? – MakeUseOf
If you’ve ever seen a “Windows has detected an IP address conflict” or “another computer on this network has the same IP address” message, you might wonder what this warning means. While IP conflict issues aren’t usually difficult to fix, they are confusing, especially for those new to networking.
Let’s look at what an IP address conflict is, whether two devices can have the same IP address, and how to resolve this error when it pops up.
What Is an IP Address Conflict?
An IP address conflict occurs when two or more devices on the same network are assigned the same IP address. To explain why this is a problem, we must take a step back and look at what IP addresses are for.
Like a physical home address for receiving mail, IP addresses act as a way to identify your computer on a network. Your router uses those IP addresses to direct network traffic to the right devices. Check out our explanation of how routers work for more details on this.
Because of this setup, no two devices can have the same IP address on one network. If this happens, the network becomes confused by the duplicate IP addresses and can’t use them correctly. Think about mail delivery trying to find the right mailbox if two houses on the same street had the same number; it’s the same way for your home network.
Keep in mind that we’re only talking about private IP addresses here, which refers to addresses used on your own network. Public IPs are how the rest of the internet sees any device on your network, but they aren’t relevant to this discussion about duplicate IP conflicts.
Since two computers cannot have the same IP address, how does the duplicate IP error occur?
How Does an IP Address Conflict Happen?
Under most circumstances, in modern home networks, IP conflicts are rare. This is because of DHCP (Dynamic Host Configuration Protocol), a system that routers use to hand out IP addresses.
With DHCP, when you connect a new device to your network, your router chooses an available IP address from the pool of options. The device uses this IP for some time, until the lease expires and it has to get a new IP from the router.
Unless your router malfunctions, two devices should never get the same IP address under this system. Your router knows which IP addresses are already in use and won’t give them out twice.
More commonly, an IP conflict can occur when you assign static IP addresses on your network. Instead of DHCP automatically choosing an address for all devices, a static IP lets you specify a certain IP address that a network device will always use.
If you mistakenly assign the same static address to two devices, you’ll run into a duplicate IP error. This problem can also arise if you set a device to use a static IP without reserving that address in your router. Eventually, your router will try to hand out that address to another device, creating an IP conflict.
Another IP conflict scenario can occur if you have two DHCP servers on your network (which you should avoid). For example, you might have your own wireless router connected to your ISP’s modem and router combo. If both devices are trying to act as a router, they might hand out duplicate IP addresses.
Finally, you can potentially introduce duplicate IPs onto your network when a machine comes back online after being in standby mode.
For instance, say you leave your laptop in a hibernated state for two weeks. During that time, your router may recall the laptop’s IP address and assign it to another device, like your phone. When you turn the laptop back on, your computer might think it still owns that IP address, which results in an IP conflict with your phone.
This could also occur if you put your computer in standby on another network that uses the same IP pool as yours, then bring it home and reconnect to your network. If that IP is already in use, you’ll see an IP conflict error.
How to Fix IP Address Conflicts
Like all home network troubleshooting, the first step you should take to fix duplicate IP problems is restarting the affected computer and your networking equipment.
The IP address error could have been a small glitch, which a reboot will resolve. Restarting your router and modem (if they’re separate devices) will re-assign all IP addresses via DHCP.
If restarting everything doesn’t work, the problem is a little deeper. You should next check to see if your computer is using a static IP address.
Troubleshooting Duplicate IP Addresses on Windows
To do so on Windows, open Settings and go to Network & Internet > Status. Click Change adapter options on this menu, then double-click the name of your network connection in the resulting window. This process will take you through a few different dialog boxes.
In the Status window, click Properties, followed by double-clicking Internet Protocol Version 4. This menu should have Obtain an IP address automatically selected. If there’s a manual IP address listed, select the automatic option instead and hit OK.
Repeat these steps for Internet Protocol Version 6 (if applicable) and see if the conflict goes away.
You should also try releasing your computer’s current IP address and obtaining a new one. Restarting does this too, but it’s still worth a try at this time. To do so, right-click on the Start button (or hit Win + X) and select Command Prompt or Windows PowerShell.
In the terminal window, type the following command to give up your current IP, followed by Enter:
After this, use the following command to obtain a new IP address from the router:
Troubleshooting IP Conflicts on a Mac
On a Mac, you’ll find IP address options under Apple menu > System Preferences > Network. Select the connection type you’re using from the left side, then click Advanced.
On the resulting page, select the TCP/IP tab. If the Configure IPv4 box is set to Manually, change it to Using DHCP. Check that Configure IPv6 is also set to Automatically (if it’s not disabled), then hit OK.
To refresh your current IP on a Mac, click the Renew DHCP Lease button to the right on this page.
Check Your Router for IP Address Conflicts
If the above steps didn’t fix the duplicate IP issue on your network, you should next log into your router’s administration panel and take a look at the connected devices. How you do this will depend on your router model, so we can’t give exact instructions for each case. Have a look at our router management intro guide for help understanding the interface.
Typically, you’ll find a list of connected devices under a section titled Attached Devices, Connected Devices, My Network, or similar. Have a look at each device and keep an eye out for duplicate IP addresses.
To help narrow this down, you can check the IP address of your computer by typing ipconfig into a Windows Command Prompt or ifconfig into the Mac terminal. Then you’ll know the IP address that’s being duplicated, making it easy to look for in the list.
If you find two devices with the same address, remove any static IP address settings, or refresh their IPs in your router to resolve the conflict.
In general, you shouldn’t need to worry about static IPs in simple home settings, so it’s best to let your router handle all this. If you do need to reserve an IP address for some reason, make sure it’s set in your router so it doesn’t hand out a duplicate.
Update Your Router Firmware
A faulty router can cause IP conflicts to occur more frequently, and without warning. If you continue to have IP address errors even after performing the above troubleshooting, you should update your router’s firmware.
The exact steps to this also depend on the router you have. Usually, you’ll find a Firmware Update option when you log into your router’s admin panel. This may be under an Advanced or Tools menu.
While some routers let you update the firmware automatically through the management panel, others require you to download a file from the manufacturer and upload it to your router. Check your router manufacturer’s website for more help if needed.
Resolve IP Address Conflicts Peacefully
Now you know what an IP address conflict is, how two devices could get the same IP address, and how to fix duplicate IP conflicts. Most of the time, a conflict won’t occur on your home network unless you’ve messed around with static IP options. And if a duplicate IP problem does arise, you can usually resolve it by setting all devices to use DHCP.
To go deeper into home networking, you should also learn about MAC addresses and how they work with IP addresses.
Understanding IP and MAC Addresses: What Are They Good For? The internet isn’t so different from the regular postal service. Instead of a home address, we have IP addresses. Instead of names, we have MAC addresses. Together, they get the data to your door. Here’s how.
About The Author
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Ben is a Deputy Editor and the Onboarding Manager at MakeUseOf. He left his IT job to write full-time in 2016 and has never looked back. He’s been covering tech tutorials, video game recommendations, and more as a professional writer for over seven years.
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What is an IP Address Conflict & What to Do About It | Allconnect
At Allconnect, we work to present quality information with editorial integrity. While this post may contain offers from our partners, our opinions are our own. Here’s how we make money. “There is an IP address conflict with another system on the network. ” What? Those dreaded words pop up on your PC, inciting confusion and frustration. Conflict? Me? With who? Why? Before you freak out and cue Wanna Be Startin’ Somethin’, let’s start at the beginning, so we understand what’s going on. And then we’ll get to some fairly simple starters, what’s an IP address? Your IP address is the unique string of numbers, joined by periods, that identifies your device, whether it be a computer, tablet, smartphone, etc. The IP stands for “internet protocol” and it basically allows devices to transmit data back and forth and communicate across networks. So, in short, without IP addresses, data wouldn’t know where to travel over the internet. It’s kind of like an address and return address on snail mail. With that information, the mail carrier knows not only where to send the information, but where to return it. When you visit a website, your device gives the website your unique IP address. The IP address includes information about your location and allows the site to send the information you’re requesting to the right, onto the Red AlertOne of the most common error messages that pops up when you have an IP address issue is: “There is an IP address conflict with another system on the network. ”So what’s going on? For a system to communicate via a network, it must have a unique IP address. Conflicts arise when two devices are on the same network trying to use the same IP address. When this occurs, both computers end up not being able to connect to network resources or perform other network should you do first? First, it may sound silly, but try restarting your computer. Yes, sometimes machines simply get “stuck” and need a reboot, and often that will solve this that doesn’t help, Microsoft tells us that the best way to solve this issue is to:Click Start and select “cmd” in the box and click OK. A window with a command prompt with an old-school DOS aesthetic “ipconfig /release” and press Enter. This should release your computer’s current IP “ipconfig /renew” and press Enter. This assigns your computer a new set of IP Exit and press Enter to close that that still doesn’t work, an additional method is to change the TCP/IP settings. These settings essentially instruct your computer how to communicate with others. To do this, Microsoft recommends using automated Dynamic Host Configuration Protocol (DHCP), which automatically assigns IP addresses to your network’s computers. To enable your DHCP or change your TCP/IP settings:Select Start, select Settings > Network & Wi-Fi > Manage known networks, if you have a Wi-Fi network. Choose the network you want to change the settings for, and select Properties. (For an Ethernet network, select Ethernet) IP assignment, select Edit IP settings, select Automatic (DHCP) or specify IPv4 settings manually:Under Edit IP settings, select Manual, then turn on IPv4. To specify an IP address, in the IP address, Subnet prefix length, and Gateway boxes, type the IP address specify a DNS server address, in the Preferred DNS and Alternate DNS boxes, type the addresses of the primary and secondary DNS specify IPv6 settings manually:Under Edit IP settings, choose Manual, then turn on specify an IP address, in the IP address, Subnet prefix length, and Gateway boxes, type the IP address specify a DNS server address, in the Preferred DNS and Alternate DNS boxes, type the addresses of the primary and secondary DNS you select Automatic (DHCP), the IP address settings and DNS server address setting are set automatically by your router or other access point (recommended) you select Manual, you can manually set your IP address settings and DNS server Save. Still not fixed? Lucky you. In some rare cases, like if you experience chronic IP conflicts, you may need to update your firmware. At this point, it’s possible that your DHCP server has malfunctioned and assigned two computers identical IP addresses, leading to consistent conflicts. In this case, you’ll want to try to update a driver for hardware that isn’t working cording to Microsoft, it’s best to allow Windows to install device drivers automatically. But if Windows cannot locate your device’s driver, you can do some digging on the manufacturer’s website. Once you find the updated driver, follow the installation prompts. Some devices are tricky and include drivers you’ll need to install. If you download a driver that isn’t self-installing, try this: Make sure you’re logged in as an Device Manager. (To get there, click Start, Control Panel, System and Security, Device Manager. )In the hardware list, find the device you’d like to update. Double click that device’s name. Click on the Driver Update Driver, and then follow the prompts. You should be all set! Now, if for some reason, you need to change your IP address, we’ve got you covered. For more guidance on internet troubleshooting, be sure to bookmark our Resource Center. Easy ways to fix a 403 forbidden error message Maria LeLaurin — 3 min read How to find your router IP address Allconnect — 5 min read What is my IP address and why does it matter? Taylor Gadsden — 4 min read Latest Saturday, October 2, 2021 Elon Musk’s Starlink is not the lone solution to the digital divide Ari Howard — 4 min read Monday, September 27, 2021 Trust in technology fell to an all-time low in 2021. Here’s why we’re losing faith. Joe Supan — 6 min read Saturday, September 25, 2021 What is a Comcast lift zone? Ari Howard — 2 min read
How many computers can have the same public IP? – Server Fault
I’ve got a list of hundreds of page requests from the same IP and I need to know if these could be requests by different computers.
voretaq778. 6k17 gold badges126 silver badges212 bronze badges
asked Aug 31 ’11 at 14:13
There is no limit to the number of computers, however there is a limit to the number of simultaneous connections because of the possibility of ephemeral port exhaustion. More computers usually means more connections so there is a practical limit to how many computers will typically share the same IP address. Usually with a very large number of computers, multiple IP addresses will be shared in a pool to be used for NAT.
answered Aug 31 ’11 at 15:53
Jason BergJason Berg18. 8k6 gold badges37 silver badges55 bronze badges
Besides NAT, they could be behind a proxy. if the proxy is nice to you, you might find more informations in the HTTP-Headers of the requests. Look for X-Forwarded-For headers, which might help you to get closer to your real usercount.
answered Aug 31 ’11 at 14:58
Silent-BobSilent-Bob1, 0666 silver badges9 bronze badges
Even better, you could have a single computer behind a corporate gateway use a different IP on each hit, because of a load-balancing reverse proxy. Don’t use IP as identifier. Just don’t.
answered Aug 31 ’11 at 18:23
It’s fairly typical for an ISP to give a customer just one IP address. In order for a router to allow multiple users on a private network to utilize this address it uses NAT (Network Address Translation).
answered Aug 31 ’11 at 14:15
SpacemanSpiffSpacemanSpiff8, 7031 gold badge22 silver badges35 bronze badges
Of course they can.
If you’re on a network and you have 1 public IP address, each page request (even if it comes from different computers) still comes from the same IP address.
answered Aug 31 ’11 at 14:16
DKNUCKLESDKNUCKLES4, 0087 gold badges43 silver badges60 bronze badges
There can be any number of computers on a LAN (It may depend on the physical medium used between them i. e. cables, repeaters etc. ), normally there is a single Gateway (at least one is required) to connect to the Internet. These Gateways normally have multiple IPs (both private and public) for the communication.
Now as the LAN can inturn be set of LANs… figuring out the correct client is a herculean task if not impossible… Though you can still get to that by looking to the routing tables of Gateway or by accessing Link may help
Most of the times public IP is used by ISPs and Large or Mid size Organizations… That is why using client IP is not considered a wise idea now a days.
answered Sep 1 ’11 at 12:27
AmitAmit2112 silver badges7 bronze badges
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Frequently Asked Questions about two computers with same ip address
What if 2 computers have the same IP address?
For a system to communicate via a network, it must have a unique IP address. Conflicts arise when two devices are on the same network trying to use the same IP address. When this occurs, both computers end up not being able to connect to network resources or perform other network operations.Feb 23, 2020
How many computers can use the same IP address?
7 Answers. There is no limit to the number of computers, however there is a limit to the number of simultaneous connections because of the possibility of ephemeral port exhaustion. More computers usually means more connections so there is a practical limit to how many computers will typically share the same IP address.