IP address conflicts occur when two devices on the same network are assigned the same IP, either manually or through DHCP malfunctions. As a developer, you'll want to:

• Identify all active devices
• Resolve duplicate IP assignments
• Maintain network inventory

For quick scans without third-party tools, use these built-in Windows commands:

# Basic ARP scan (shows recently contacted devices)
arp -a

# Ping sweep batch script example
@echo off
for /l %%i in (1,1,254) do ping -n 1 192.168.1.%%i | find "Reply"

For more comprehensive scanning with device names:

# PowerShell advanced network scanner
$subnet = "192.168.1"
$range = 1..254
$timeout = 100

$devices = foreach ($i in $range) {
    $ip = "$subnet.$i"
    $ping = New-Object System.Net.NetworkInformation.Ping
    try {
        $reply = $ping.Send($ip, $timeout)
        if ($reply.Status -eq "Success") {
            $hostname = try { [System.Net.Dns]::GetHostEntry($ip).HostName } catch { "Unknown" }
            [PSCustomObject]@{
                IP = $ip
                Hostname = $hostname
                MAC = (arp -a | Select-String "$ip\s+(\S+)").Matches.Groups[1].Value
                Status = "Active"
            }
        }
    } catch {}
}

$devices | Format-Table -AutoSize

For larger networks, consider these developer-friendly tools:

• Nmap:

  nmap -sn 192.168.1.0/24 --script hostmap-crtsh

• Angry IP Scanner: Can be automated through command line with XML output
• Advanced IP Scanner: Provides REST API for integration with monitoring systems

When conflicts are detected:

# Force DHCP release/renew on Windows
ipconfig /release
ipconfig /renew
ipconfig /flushdns

For continuous monitoring, implement a simple Python listener:

import scapy.all as scapy
from collections import defaultdict

device_counts = defaultdict(int)

def packet_handler(pkt):
    if pkt.haslayer(scapy.IP):
        ip_src = pkt[scapy.IP].src
        device_counts[ip_src] += 1

scapy.sniff(prn=packet_handler, timeout=60)
print("Active devices:", device_counts)

When Windows throws the "There is an IP address conflict" alert, it means multiple devices are fighting for the same IP on your local network. As developers, we need precise tools to audit LAN devices programmatically rather than just clicking through GUI utilities.

Before reaching for third-party solutions, try these built-in Windows commands:

REM Basic IP scan using ARP
arp -a

REM Advanced discovery with hostnames
nbtstat -a [IP_ADDRESS]

REM Full network scan (PowerShell)
1..254 | % {ping -n 1 -w 100 "192.168.1.$_" } | Select-String "Reply"

For developers who need structured data output, this PowerShell script provides JSON-ready results:

function Get-NetworkDevices {
    $subnet = "192.168.1"
    $devices = @()
    
    1..254 | ForEach-Object {
        $ip = "$subnet.$_"
        if (Test-Connection -ComputerName $ip -Count 1 -Quiet) {
            try {
                $hostname = [System.Net.Dns]::GetHostEntry($ip).HostName
                $mac = (arp -a $ip | Select-String "([0-9A-F]{2}(?:-[0-9A-F]{2}){5})").Matches.Value
                $devices += [PSCustomObject]@{
                    IP = $ip
                    Hostname = $hostname
                    MAC = $mac
                }
            } catch { $devices += [PSCustomObject]@{IP=$ip; Hostname="Unknown"; MAC=""} }
        }
    }
    
    return $devices
}

Get-NetworkDevices | ConvertTo-Json -Depth 2

For cross-platform compatibility, this Python solution uses scapy:

from scapy.all import ARP, Ether, srp
import socket

def scan_network(ip_range="192.168.1.1/24"):
    arp = ARP(pdst=ip_range)
    ether = Ether(dst="ff:ff:ff:ff:ff:ff")
    packet = ether/arp
    
    result = srp(packet, timeout=3, verbose=0)[0]
    
    devices = []
    for sent, received in result:
        try:
            hostname = socket.gethostbyaddr(received.psrc)[0]
        except:
            hostname = "Unknown"
            
        devices.append({
            'ip': received.psrc,
            'mac': received.hwsrc,
            'hostname': hostname
        })
    
    return devices

print(scan_network())

While built-in tools work, sometimes you need more features:

• Angry IP Scanner: Best for quick GUI scanning with export options
• Advanced IP Scanner: Provides remote control via RDP/SSH
• Nmap: The ultimate network discovery tool for security professionals

For automated conflict resolution in Python:

import os
import re

def detect_ip_conflicts():
    result = os.popen('arp -a').read()
    ip_mac = {}
    
    for line in result.split('\n'):
        match = re.search(r'(\d+\.\d+\.\d+\.\d+).*([0-9A-F]{2}-[0-9A-F]{2}-[0-9A-F]{2}-[0-9A-F]{2}-[0-9A-F]{2}-[0-9A-F]{2})', line)
        if match:
            ip, mac = match.groups()
            if ip in ip_mac and ip_mac[ip] != mac:
                print(f"CONFLICT DETECTED: {ip} is claimed by {mac} and {ip_mac[ip]}")
            ip_mac[ip] = mac
            
    return ip_mac

detect_ip_conflicts()