[SOLVED] Incorrect DHCP address release

RouterOS Beginner Basics
1

Good Day,

I am a part time sysadmin working in a small repair shop which is divided across two buildings, having two independent network connections. In both of the buildings I have Mikrotik RB751U-2HnD running ROS 6.37.5. They are connected via PPTP as we have SAMBA running for file sharing between buildings. Yesterday I had a minor issue with one of our Windows 7 clients, after a reboot I noticed that the IP address on the client is given from the range of our first router. Please see the attached logs from both routers:

Router 1 - https://pastebin.com/raw/AuNibFYc
Router 2 - https://pastebin.com/raw/WHPQ6Eyf

DHCP lease on Router 2 - https://pastebin.com/raw/536ThQp7

As you can see in the last log, some of my clients are given a ciaddr which is outside the scope of the second router’s dhcp pool.

Thank you!

2

Good day,

I have managed to find the root cause of this problem as I have a another router which is managed by our security company and is connected to a switch on which my RB751 is connected. As it turns out, our clients will get a lease from the DHCP server which is closest to them. I tried to apply the solutions described here - http://forum.mikrotik.com/t/exact-steps-to-block-rogue-dhcp-servers/20839/1 But they did not work for me. My solution was to disable the DHCP server on security company’s router.