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Windows Server 2025: What Enterprise IT Needs to Know

gbwise10 February 20257 min read

The Big Picture

Windows Server 2025 represents Microsoft's continued push toward hybrid cloud infrastructure. For enterprise IT teams, the key themes are security by default, improved Active Directory, and tighter Azure integration. Here's what you need to know to plan your upgrade strategy.

Security Improvements That Matter

Credential Guard by Default

In Windows Server 2025, Credential Guard is enabled by default on supported hardware. This isolates NTLM password hashes and Kerberos tickets in a hardware-backed virtual secure mode, making pass-the-hash attacks significantly harder.

TLS 1.3 Everywhere

TLS 1.3 is now the default protocol for all encrypted communications. Older protocols (TLS 1.0, 1.1) are disabled out of the box. If you have legacy applications that depend on older TLS versions, plan your compatibility testing now.

SMB Signing Required

SMB signing is now mandatory for all connections, closing a long-standing vector for man-in-the-middle and relay attacks. This is a breaking change for environments with older clients — test thoroughly.

Active Directory Enhancements

32k Database Page Size

Active Directory now supports a 32KB database page size (up from 8KB). For large enterprises, this means:

  • Support for more than 1,600 values per multi-valued attribute
  • Better performance for complex group memberships
  • Improved replication efficiency

Improved Replication

Cross-site replication has been optimised with better compression and delta synchronisation. For organisations with dozens of domain controllers across multiple sites, this translates to reduced bandwidth usage and faster convergence.

Hyper-V and Virtualisation

GPU Partitioning

Hyper-V now supports GPU partitioning (GPU-PV), allowing multiple virtual machines to share a physical GPU. This is significant for:

  • VDI deployments requiring GPU acceleration
  • AI/ML workloads in virtualised environments
  • CAD and engineering applications

Live Migration Improvements

Live migration now supports running migrations over RDMA networks with significantly reduced transfer times. For large VMs (100GB+), migration times can be cut by 50-70%.

Azure Hybrid Integration

Azure Arc Deep Integration

Windows Server 2025 includes native Azure Arc agent capabilities, allowing:

  • Azure Policy enforcement on-premises
  • Azure Monitor integration without additional agents
  • Microsoft Defender for Cloud protection
  • Azure Update Manager for patching

Hotpatching

Available with Azure Arc, hotpatching allows security updates to be applied without rebooting. For environments where uptime is critical, this eliminates the monthly reboot window for security patching.

Storage and Networking

Storage Spaces Direct Improvements

  • NVMe performance optimisations for all-flash deployments
  • ReFS improvements for better data integrity
  • Storage replica enhancements for cross-site redundancy

Network ATC

Network ATC (Advanced Transition Control) simplifies network configuration for clustered environments. Instead of manually configuring NICs, VLANs, and QoS, you declare your intent and Windows handles the implementation.

Migration Planning

If you're running Windows Server 2019 or 2022, here's your migration checklist:

  • Audit your current environment — document all roles, features, and custom configurations
  • Test TLS 1.3 compatibility with all applications
  • Verify SMB signing won't break legacy clients
  • Plan Active Directory upgrade path (forest and domain functional levels)
  • Review GPU requirements if using Hyper-V
  • Test in a lab environment before touching production

Plan for a 3-6 month migration window for enterprise environments. Don't rush it — the security defaults alone require thorough compatibility testing.

Should You Upgrade?

If you're running Windows Server 2016 or earlier, the answer is unequivocally yes — you're running out of support runway and missing critical security features.

For Windows Server 2019/2022 environments, the decision depends on your specific needs. The Azure hybrid features and security improvements are compelling, but only if your applications are ready.

Need help planning your Windows Server 2025 migration? Contact our team — we've been running preview deployments since day one and can help you build a smooth transition plan.