Why are there identical IP addresses on the DNS server?

Question

Network administration

On a DNS server (Windows 2012 R2), the organization's forward lookup zone has the same IP addresses assigned to different users. There are no complaints about the conflict of IP addresses. Where to look and what to do? The DHCP server is a Mikrotik rb750 with a strictly defined address pool without reservation.

spoiler

Answer 1

What surprises you? Different names point to the same device, this is normal.

Answer 2

The addresses are issued by the DCHP server, the lease has expired, the name remains. Because in AD, machines have the right to register records in dns automatically.
You need to configure DNS Aging and Scavenging so that old records are also cleaned up automatically.

Answer 3

Reinstalled Windows or changed the name of the computer. The Mac address remained old, so Mikrotik issued the same address.

Answer 4

You have already been told about setting up DNS Aging\Scavenging.
And so that computers do not register themselves in DNS, but DHCP does this and so that there are no unnecessary duplicates, you need to transfer DHCP to WIndows Server and give DHCP the right to update records in DNS.
To do this, you need to create a service (user account) account in AD, add it to the DNSUpdateProxy group and enter the login and password in the DHCP settings.
https://www.serverbrain.org/implementing-2003-netw...
https://support.microsoft.com/en-us/help/816592/ho...