2026-04 Update Breaks Domain Logins
I have an Active Directory domain that is old (from 2000!) that has been upgraded and moved to newer versions of Windows Server and Active Directory. I have domain controller VMs running Windows Server 2025 Standard Edition. Unfortunately they installed the latest 2026-04 patches which my have changed the Kerberos encryption from RC4 to AES. This has resulted in my not being able to log into any Active Directory domain accounts and the domain controllers themselves. I can only log into workstations using the local account. Suffice to say this a nightmare. Any ideas how to fix it since I can't access the usual tools like Active Directory Users and Computers, Hyper-V won't connect to the VMs, etc. Thanks. S
Procedures to raise the functional level of AD 2008 r2 to 2019
Hello everyone, Our AD has the Windows Server 2008 functional level and the servers with Windows Server 2016 OS. I intend to raise the functional level to 2019 or 2025. I would like your help with tips and documentation to decide whether 2019 or 2025 would be best, what are the risks and procedures for successful migration. I have an isolated environment to carry out rehearsals and tests before actually going into production.
Error al agregar Windows Server 2025 a dominio existente, nivel funcional 2016
Buenas a todos, Me dirijo a esta comunidad en busca de orientación para resolver un problema que se me está presentando al intentar integrar un nuevo servidor con Windows Server 2025 Standard a mi infraestructura de Active Directory existente. Descripción del entorno: Dominio de Active Directory activo con Windows Server 2019 Standard. Nivel funcional de dominio y bosque configurado en Windows Server 2016. Controladores de dominio actuales: server-dc01.impresoratec y server-ad2019.impresoratec. El nombre de dominio interno utilizado es impresoratec (nombre NetBIOS/dominio de etiqueta única, sin sufijo DNS completo tipo .local o .com). Problema: Al intentar agregar el nuevo servidor con Windows Server 2025 al dominio, el proceso falla y se presenta el siguiente mensaje de error: "Es posible que el nombre de dominio "impresoratec" sea un nombre de dominio NetBIOS. Si este es el caso, compruebe que el nombre de dominio está registrado correctamente con WINS. [...] La consulta se refería al registro SRV para _ldap._tcp.dc._msdcs.impresoratec. La consulta identificó los siguientes controladores de dominio: server-dc01.impresoratec y server-ad2019.impresoratec. Sin embargo, no se pudo contactar con ningún controlador de dominio." El mensaje sugiere que los registros de host (A) o (AAAA) pueden contener direcciones IP incorrectas o que los controladores de dominio no son accesibles desde el nuevo servidor. Lo que he verificado hasta ahora: Los controladores de dominio existentes están en línea y operativos. La replicación entre los DCs actuales funciona con normalidad. El nuevo servidor con 2025 tiene conectividad de red general, pero no logra localizar los DCs al momento de unirse al dominio. Mi consulta: ¿Alguien ha experimentado este comportamiento al incorporar un servidor con Windows Server 2025 a un dominio con nivel funcional 2016 y un nombre de dominio de etiqueta única (single-label domain)? ¿Existe algún requisito previo adicional —como la actualización del esquema de AD, ajustes en DNS o en WINS— que deba cumplirse antes de agregar el nuevo DC? Agradezco de antemano cualquier orientación o experiencia que puedan compartir.
How to add a new domain controller to an existing Active Directory domain?
The specific situation is as follows: The company has one forest and domain, and two Active Directory (AD) servers. These two servers communicate and synchronize data. One server is deployed in the local data center, and the other is deployed on Azure Cloud. The forest and domain functional levels are both Windows Server 2008 R2. Both servers are running Windows Server 2016 Standard. Because there are computers running Windows XP and Windows 7 in the domain, upgrading the forest and domain functional levels is not possible. Windows Server 2008 R2 must be retained. The company now needs to add a new AD server on Huawei Cloud and join it to the company's forest and domain. The main questions are: How do I determine which operating system the new server should run? Excluding Windows Server 2016. How should I choose between Windows Server 2019, 2022, and 2025? How do I determine how to allocate CPU, memory, disk, and network resources during system deployment? How to determine which operating system is best suited for running a domain controller without conflicts or incompatibility? What preparations should be made before deploying a new server?Beyond RC4 for Windows authentication - Question regarding KB5073381
In KB5021131 MS recommends setting the value for DefaultDomainSupportedEncTypes to 0x38, in the new KB 5073381 it's 0x18. This removes the setting that forces "AES Session Keys" which should be fine if Kerberos Tickets can only use AES Encryption. But what about accounts that have RC4 enabled in their msds-supportedEncryptionTypes attribute? They could still use RC4 for Kerberos ticket encryption and would then also fallback to RC4 session ticket encryption. As far as I believe the DefaultDomainSupportedEncTypes was explicitly introduced to avoid this scenario. Or is there now some hard-coded mechanism that always ensures that Session Keys are AES encrypted?
Lots of DNS Server events 5504 on AD DNS server from Cloudflare etc
Hi! I'm getting about 18 events with id 5504 while trying to resolve some DNS names, like fullfiles.xyz. The DNS server is configured to use provider DNS and root hints. I can suppress these messages by disabling root hints or by disabling EDNS0 with dnscmd /config /enablednsprobes 0. I tried to use packet capture on the DC and on the router, and analyzed the results with AI, which answered: "You receive malformed patterns on the WAN interface." Can anybody explain the cause of this problem? Any ideas to fix it? Thanks!
Issues with Group Policy Update (gpupdate)
I am getting an error when I attempt to perform a gpupdate /force on workstations. I have checked the health of the DC's and find no issues. I am going to include a screenshot of the error - hoping someone can guide me as on how to resolve. The system will say to reboot but the policy never seems to run just keeps prompting for reboot.
