Users are getting BAD_IP_ADDRESS

[mohd-shakir]

Hi Team,

Users in my network are receiving bad IP addresses, and our DHCP scope is set up on a Microsoft Windows Server.

Please assist me in resolving this issue and let me know if you need any information from my side.

[MHM Cisco World]

What is SW plat? 

MHM

[M02@rt37]

Hello @mohd-shakir 

Cloud you please more elaborate about "bad address" ?

Wifi users only ? 

Do you see here ? https://learn.microsoft.com/en-us/answers/questions/104532/bad-address-causing-dhcp-to-fill-up

[Torbjørn · Accepted solution]

"Bad address" here means that there is an IP conflict. So there is either another DHCP server for that subnet, or someone has assigned their machines static IP addresses. The second option is more common

You should probably track down the clients in question(Check ARP on the router, follow the MAC address to the switchport) and resolve the issue. Alternatively you can enable dynamic ARP inspection so that the clients won't be able to communicate using their non-DHCP assigned addresses.

[MHM Cisco World]

Run of IP is normal and it happened to guest witeless user

Bad-address is abnormal and it happened mainly when 

You config DHCP pool conflict with SVI or L3 router interface

How can I know that 

Simply do 

Show ip interface breif 

See how many IP share same subnet with dhcp pool

MHM

[pieterh]

the BAD_ADDRESS in the screenshot is not about a bad IP-address!,
it is an IP-address where no DNS records is attached (anymore)
you must investigate the column  that begins with "This address...." to see the real error message

[zaheernew]

Dear  

A detailed solution is give below;

1. Bad IP Address (Intro)

When users receive bad IP addresses (commonly in the 169.254.x.x range), it indicates that their devices were unable to contact a DHCP server to get a valid IP configuration. This could be due to DHCP server issues, network misconfiguration, rogue DHCP servers, or even temporary disconnections.

Symptoms may include:

No internet access

Wrong subnet or gateway

Limited connectivity

Devices getting stuck with 169.254.x.x addresses

2. How to Diagnose the DHCP Windows Server

a. Check Scope Settings

Go to Server Manager > Tools > DHCPOr run dhcpmgmt.msc

Expand the IPv4 scope and verify:

Address Pool: Start and End range is valid

Exclusions: Ensure not too many IPs are excluded

Leases: Check current usage – scope might be exhausted

Reservations: Ensure no conflicts

Scope is Active (Right-click > Activate if not)

b. Confirm Server Status

Make sure the DHCP Server service is Running

services.msc > DHCP Server > Status: Running

Open Event Viewer > Applications and Services Logs > Microsoft > Windows > DHCP-Server

Look for any warnings or errors about address exhaustion or network binding

️ 3. Use Tool – Advanced IP Scanner (or Similar)

Download Advanced IP Scanner on a connected PC and scan your network:

This will help you:

Identify all active IP addresses and hostnames

Detect unknown/unauthorized DHCP servers

Check if any non-DHCP devices are assigning IPs (like an ISP modem/router)

What to look for:

Devices with IPs outside your intended DHCP range

Duplicate or conflicting IPs

Strange vendor MAC addresses (like from ISP routers)

If you detect another DHCP server (e.g., an ISP modem/router), you must disable its DHCP feature.

🕵️ 4. Monitored – Are There Any Devices Like ISP Broadband Plugged into the Live Network?

This is common in branch offices or small setups: an ISP router or mobile broadband device (with DHCP enabled) is connected to the LAN switch.

These can conflict with your official DHCP server, causing random devices to get wrong IPs.

What to do:

Trace the physical network – especially check switches for unknown uplinks

Identify all routers/modems on the LAN

Login to the router's admin page (if accessible) and disable DHCP

🧑‍ 5. Client-Side – IP Address Release and Renew

On affected client systems (Windows):

Open Command Prompt and run:

ipconfig /release

ipconfig /renew

ipconfig /all

This forces the device to drop its current IP and request a fresh one.

After renewal, confirm:

IP address is within correct DHCP range

Subnet mask and default gateway are correct

DNS server is the expected one (often your internal DNS or the DHCP server)

If clients still get 169.x.x.x or wrong IPs, the issue is likely server-side or network path-related.

6. Restart the DHCP Server

If none of the above resolves the issue, try restarting the DHCP service or even the server itself.

To restart only the DHCP service:

services.msc > DHCP Server > Restart

OR Open PowerShell (as Admin):

Restart-Service -Name dhcpserver

If DHCP still misbehaves:

Consider restarting the server (during off-peak hours)

Rebind DHCP to correct network interfaces (in DHCP console)

🧩 Final Checks and Prevention Tips:

Enable DHCP Snooping on managed switches to prevent rogue DHCP servers

Avoid connecting consumer ISP routers directly to LAN switches

Regularly review DHCP lease reports

Monitor Event Viewer logs weekly

Let me

know if you'd like help checking the scope file, leases, or DHCP logs from your server. If you can share:

DHCP scope screenshot

ipconfig /all from a problem client

Results of Advanced IP Scanne

[balaji.bandi · Accepted solution]

This may be causing different reasons, fist i would suggest to trace the IP and see any Duplicate IP already configured and available in the network ?

Also good practice in DHCP - Make static reservation if any device need to static IP and exclude the range, so this will be not allocated from DHCP pool avoid this kind of situation.

[wajidhassan]

Hi @mohd-shakir 

The BAD_IP_ADDRESS error usually means there’s an IP conflict or the DHCP server is offering addresses that are already in use.

To resolve this, please check:

• That no static IPs overlap with your DHCP scope.

• The DHCP scope has enough free addresses.

• Lease duration isn’t too long, preventing address recycling.

• No rogue DHCP servers are on the network.

• Network connectivity between clients and the DHCP server is intact.

Also, review your DHCP server logs for any related errors.

This should help address the issue.

[mohd-shakir]

Issue has been resolved and thanks everyone for your support.

Have a good day.

[songohan3548]

Users in my network are receiving bad IP addresses, even though our DHCP scope is configured on a Microsoft Windows Server. This is causing connectivity issues across multiple devices. I’d appreciate your assistance in identifying and resolving the problem. If needed, I can provide additional details or configuration snapshots. We’re currently evaluating options with U.S.-Based Microsoft Power Automate Workflow Automation Experts  to streamline some of our network diagnostics and automate future alerts, but we’d first like to address the root issue here. Please let me know what further information you require from my side. Thank you.

[pieterh]

Hi @songohan3548 ,
1) you'd better make this a new post instead of hijacking someone other's post that is already marked as solved.
2) did you read this whole post and the troubleshooting steps suggested herein?
 -> mention the troubleshooting steps you already have done in your new post