# Match the guest-cluster floating IP to its SDN VIP and probe

> How should an SDN load-balancer probe identify the active node of a guest cluster?

- Canonical URL: https://update.dsesecurity.com/updates/dse-20260908-125-match-the-guest-cluster-floating-ip-to-its-sdn-vip-and-probe/
- Publisher: Detection Systems & Engineering (DSE Security)
- Author: DSE Security Editorial Team
- Published: 2026-09-08T18:15:06+00:00
- Modified: 2026-09-08T18:23:27+00:00
- Last reviewed by DSE: 2026-09-08
- Resource type: Guide
- DSE priority: Information
- Topics: IT, Networks & Infrastructure
- Reading time: 1 minutes

## What you need to know

How should an SDN load-balancer probe identify the active node of a guest cluster?

## Potentially affected

Administrators running guest failover clusters inside SDN virtual networks.

## DSE recommendation

Create a single mapping that shows the same floating address and probe port in the cluster and load-balancer configuration.

## Article

## Source facts

Network Controller permits a VM to communicate using its assigned IP addresses. Microsoft therefore requires additional configuration for clustering that uses a floating address. Its design exposes that address through a Software Load Balancer VIP and a health probe that directs traffic to the node currently holding it. The cluster address and probe port must match the corresponding load-balancer settings. [Microsoft documentation](https://learn.microsoft.com/en-us/windows-server/networking/sdn/manage/guest-clustering).

## Applicability

Identify the guest nodes, virtual subnet, floating address, VIP, and intended probe port. Review the prerequisites for the guest cluster and reserve the actual address before adapting the example.

## DSE recommendation

Create a single mapping that shows the same floating address and probe port in the cluster and load-balancer configuration. Have the guest-cluster and SDN owners review it together. Specify which application request will prove that the active node is reachable through the published address.

## Verification

Connect through the VIP and record the responding guest node. Trigger an approved ownership move and repeat the request, checking probe state and cluster ownership during the same window. Investigate a probe mismatch or traffic reaching the wrong node before accepting the floating-address design.

## Official references

[Microsoft Learn: Guest clustering in a virtual network](https://learn.microsoft.com/en-us/windows-server/networking/sdn/manage/guest-clustering). Source reviewed September 8, 2026.

## Primary reference

- Name: Guest clustering in a virtual network
- Authority: Microsoft Learn
- URL: https://learn.microsoft.com/en-us/windows-server/networking/sdn/manage/guest-clustering
- Source publication date: Not stated by the source

## Citation and use

Preferred citation: “Match the guest-cluster floating IP to its SDN VIP and probe,” DSE Security, https://update.dsesecurity.com/updates/dse-20260908-125-match-the-guest-cluster-floating-ip-to-its-sdn-vip-and-probe/
Publishing principles: https://update.dsesecurity.com/updates/dse-updates-editorial-methodology/
Usage and citation policy: https://update.dsesecurity.com/usage/
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