Purpose
This document provides a structured procedure to identify and resolve IP address conflicts caused by overlap between statically assigned IP addresses and configured DHCP pool ranges.
Such conflicts can lead to:
Intermittent connectivity
Device communication failure
Application instability
Network performance issues
The objective is to ensure unique IP allocation and stable network operation.
Scope
Applies to enterprise and LAN environments where:
DHCP servers dynamically assign IP addresses
Some devices (Printers, Camera) use manually configured static IPs
Network devices include printers, POS terminals, cameras, NVRs, servers, and switches
IP conflicts result in intermittent or complete connectivity loss
Symptoms of Duplicate IP Conflict
Technicians may observe the following indicators:
“IP Address Conflict” warning on client devices
Intermittent network connectivity issue
Device frequently disconnecting or becoming unreachable
Duplicate IP logs observed on PC61 router
Same IP address appearing for multiple clients in Client List
ARP table showing same IP mapped to different MAC addresses
ARP entry flapping on PC61
Unstable or intermittent ping response
These symptoms suggest that two devices are attempting to use the same IP address simultaneously.
Troubleshooting Procedure
Step 1 — Identify Conflicting IP Address
Using the Pronto Cloud Controller:
Navigate to Client Page
Search for the IP address reporting conflict
Then:
Use Ping Tool (PC61 Tools section) to test connectivity
View ARP Table on PC61
View Events log for duplicate IP addresses in PCC
Confirm whether:
Multiple MAC addresses are associated with the same IP
Step 2 — Verify DHCP Pool Configuration
Open:
Network Device Page → VLAN Configuration
Check:
DHCP scope range configured for the VLAN
Example:
Subnet: 172.16.31.0/24
DHCP Pool: 172.16.31.10 – 172.16.31.200
Verify whether the conflicting IP lies inside this DHCP pool range.
Step 3 — Identify Static Device
From the ARP table:
Identify the MAC address
Trace the device via switch port mapping in MAC address table (PCC portal on Switch or device page) or physical inspection
Common static devices include:
Printers
POS terminals
Cameras
Servers
Step 4 — Confirm Root Cause
Duplicate IP conflict exists when:
A device is manually configured with an IP address within the DHCP pool range
ORDHCP server assigns an IP already manually configured on another device
This results in ARP instability and unpredictable traffic delivery.
Resolution Options
Choose one corrective action based on network design.
Option A — Modify DHCP Pool Range
Exclude static IP addresses from DHCP scope.
Example:
Static Range:
172.16.31.1 – 172.16.31.20
DHCP Pool:
172.16.31.21 – 172.16.31.200
This prevents DHCP from assigning IPs reserved for static devices.
Option B — Reconfigure Static Device
Change static device IP to an address outside DHCP pool range.
Recommended addressing structure:
Static Devices → .1 – .20
DHCP Clients → .21 – .200
Option C — Use DHCP Reservation (Preferred Method)
Instead of manual static configuration:
Configure DHCP reservation on PC61
Device will always receive same IP automatically
Benefits:
Prevents manual misconfiguration
Simplifies IP management
Verification After Fix
After corrective action:
Renew DHCP lease or reconnect client
Confirm no duplicate IP warnings
Verify ARP table shows single MAC mapping for IP
Perform stable ping test
Confirm applications operate normally
Preventive Best Practices
Maintain documented static IP allocation plan
Always separate static and DHCP ranges
Periodically audit ARP table and DHCP bindings
Prefer DHCP reservations over manual static IPs
Monitor controller logs for duplicate IP alerts
Escalation Guidelines
Escalate to Network Engineering if:
IP conflict persists after reconfiguration
DHCP scope corruption suspected
Multiple VLANs experience similar issues
Provide:
Conflicting IP address
Both MAC addresses involved
DHCP scope configuration
Switch port information
Site name and VLAN ID