I've been having IP issues with my local box for a couple months now. Usually when it starts acting up I don't have the patience to look into it, so I just drop onto DHCP, but this morning I've finally decided to figure out what's going on.
I'm on a network that has 220.127.116.11 as the gateway, and is a 255.255.254.0 subnet (so IP Range is 18.104.22.168-22.214.171.124). My static IP address is 126.96.36.199. We have a Watchguard Fireware XTM Firewall/Router that sits on 188.8.131.52 . Also, our DHCP range is 184.108.40.206-220.127.116.11
The issue is that I occasionally lose my network connection, and when I try to reconnect I get errors regarding an IP Address conflict. We're pretty strict about documenting IP addresses here, so I found it quite odd that someone else would be using my IP address. I did a couple network scans, checked my DNS and DHCP logs, and found nothing using 18.104.22.168 (aside from my computer).
Grasping at straws, I ran "arp -a" to check if that could give me any information. Oddly enough, this is what I saw (note: I am on DHCP right now):
C:\Users\jwegner>arp -a Interface: 22.214.171.124 --- 0xa Internet Address Physical Address Type 126.96.36.199 00-90-7f-42-3f-30 dynamic 188.8.131.52 00-90-7f-42-3f-30 dynamic //Truncated, because the rest is not important
Interesting - it would appear that my local computer is viewing 184.108.40.206 and 220.127.116.11 as the same device. I checked that MAC Address, and it is indeed the MAC Address for our firewall/router. I cleared my arp cache, thinking that something just got turned around somewhere. I then pinged 18.104.22.168 to recache the arp, and arp -a output the same thing.
There is nothing in my Firewall/Router that would make it take over the 22.214.171.124 address. Also, if I ping 126.96.36.199 I get nothing, so I must be getting some sort of false positive here. Any ideas on what might be causing this?