Hi @Andreas
A few comments below:
I asked the customer about WINS, but they did not know. I have never configured WINS.
This record existing because WINS naming resolution has been enabled on the zone, I would check if 10.0.0.50 has WINS installed, and also if the DHCP server is configured to provide the same IP address in the WINS server scope option to the clients. Based on your last comment the server might have already been removed.
server1 I guess is an old DC, so I can remove that as long as its gone
I would check the AD to see what domain controllers exist, or a server with DNS installed exists at this IP address, if not you should be able to remove it.
One thing I am not sure about is why the network address is added there ? 10.0.0.0 and 10.1.1.0. (FYI one of the DCs are 10.1.1.10 / 255.255.254.0 / GW 10.1.1.254.) could that be related since its a big network ?
Typically a network addresses wouldn't be added as a record, however, this address will be returned if the zone is queried for an A record, so it might be used for some other functionality.
10.1.1.50 and 10.1.1.60 I also guess are old DCs that I can remove that as long as its gone
If you can confirm that they no longer exist, you should be able to remove them.
One thing to bear in mind, these records were added for a reason, rightly or wrongly and they might still be being used, with only the information provided it's possible to provide a definitive answer if they can be removed or not, or if there will be any impact as a result of removing them. You will need to double check if the servers still exist or the configuration is being used for a specific reason in the environment.
Gary.