How to restore dhcp server on windows server 2012 R2?

Question

Domain Name System

There is a virtual DC Windows server 2012 R2. There is no backup DC yet.
There is a lot of rubbish on the physical disk where it is located, as a result, the virtual machine has stopped. I cleared the place and restarted the virtual machine. Now the DHCP server is not working normally. It is not possible to obtain an IP address via DHCP from this server, it is not possible to reserve an IP address. At the same time, those addresses that were previously reserved work fine, BUT if you remove the address from the reservation, then it will go to BAD_ADRESS and then after the lease expires, like for other computers, I will not be able to get an address from it or reserve it.
Error when trying to manually reserve an address:
An error occurred while accessing the DHCP database, see the DHCP server event log for more information about this error.
In the "Apps and Services Logs->microsoft->DHCP Server->Microsoft-Windows-DHCP Server Events/admin" log:
Event 20287 The
DHCP client request from 00155D000290 was dropped because it was in the applicable IP address ranges of the scope or superscope Scope1 no available IP addresses. The reason for this may be that there are no available IP addresses in the policy IP address ranges
In the general logs, Application log:
Event 11
Possible memory leak. Application ("C:\Windows\system32\mmc.exe" "C:\Windows\system32\dhcpmgmt.msc" ) (PID: 2572) passed a non-nullable pointer to RPC for the [out] parameter marked with [ allocate(all_nodes)]. [allocate(all_nodes)] parameters are always reallocated; if the original pointer contains a valid memory address, it will be leaked. The call arrived on the interface with UUID ({6bffd098-a112-3610-9833-46c3f874532d}), method number (18). User Response: Contact the vendor for an updated version of the application.
Event 6005 (x3 but may be related to the DHCP server event) The
winlogon notification subscriber is spending too much time processing the notification event (CreateSession).
In general logs, System log:
Event 1041
The DHCP service does not serve DHCPv4 clients because no active network interface has a statically configured IPv4 address or there are no active interfaces.
Event 1059
The DHCP service could not find a folder to authorize the server.
Event 1342
There are no available IP addresses in the IP address range of Scope1.
Event 1063
Lease scope or super scope 'Scope1' does not have an IP address.
Event 1056 (followed the recommendation of netsh dhcp server set dnscredentials - did not help)
The DHCP service has detected that it is running on a domain controller (DC) and does not have credentials configured for use with dynamic DNS registrations produced by the DHCP service. This security configuration is not recommended. Dynamic DNS registration credentials can be configured using the "netsh dhcp server set dnscredentials" command line utility or using the DHCP administration program.
Event 1065
Some orphaned configuration items were removed due to deletion of a class or parameter definition. Check the server configuration.
In short, everything is fun, I x3 what to do. There is no separate dhcp backup of the database. There is no virtual backup either. What happens if I deactivate and activate the brace? Is it necessary in this case to re-perform the backup and settings, or will it not help? The second option is to reinstall the DHCP server role?

Answer 1

In general, the method is not elegant, but if DHCP fails, it always helped me.
You need to stop the DHCP service.
Back up and delete the contents of the C:\Windows\System32\dhcp folder.
Reboot, DHCP will start. Technically, all settings will default, so you need to be prepared if there were subtle settings.
dhcp.mdb - DHCP server database file. Despite the seemingly simple structure, dancing with the removal or preliminary backup of this file does not help.
In the same folder there is a backup folder - this is an automatic backup of the dhcp server when it is restarted, but it just so happened that most often the failed version of the server gets there.
You can reinstall, but after removing the role, be sure to manually delete the C:\Windows\System32\dhcp folder - otherwise the problem will not disappear.
The main thing is not to climb into the registries, as some advise on the internet, this will only aggravate the situation.