# DHCP: IP address 192.168.1.50 conflict detected with MAC 00:11:22:33:44:55

- **ID:** `networking/dhcp-ip-conflict`
- **Domain:** networking
- **Category:** network_error
- **Verification:** ai_generated
- **Fix Rate:** 82%

## Root Cause

A DHCP server has detected that an offered IP address is already in use by another host on the network, typically due to a static IP assignment overlapping with the DHCP pool or a rogue DHCP server.

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| ISC DHCP 4.4.3-P1 | active | — | — |
| dnsmasq 2.89 | active | — | — |
| Windows Server 2022 DHCP | active | — | — |
| Linux dhcpcd 10.0.2 | active | — | — |

## Workarounds

1. **Exclude the conflicting IP from the DHCP pool and assign it as a static reservation: `dhcpd.conf: range 192.168.1.100 192.168.1.200; host static-host { hardware ethernet 00:11:22:33:44:55; fixed-address 192.168.1.50; }`** (95% success)
   ```
   Exclude the conflicting IP from the DHCP pool and assign it as a static reservation: `dhcpd.conf: range 192.168.1.100 192.168.1.200; host static-host { hardware ethernet 00:11:22:33:44:55; fixed-address 192.168.1.50; }`
   ```
2. **Run `arp -d 192.168.1.50` on the DHCP server to clear the ARP cache, then force the client to renew: `dhclient -r && dhclient`** (80% success)
   ```
   Run `arp -d 192.168.1.50` on the DHCP server to clear the ARP cache, then force the client to renew: `dhclient -r && dhclient`
   ```

## Dead Ends

- **** — The conflicting IP is still in the pool and may be reassigned, causing the same conflict again unless the pool or static assignment is fixed. (75% fail)
- **** — Longer leases make conflicts persist longer and do not address the root cause of overlapping addresses. (65% fail)
- **** — This hides the problem but allows duplicate IPs to be assigned, leading to intermittent connectivity issues and ARP conflicts. (90% fail)