---
title: "Known Limitations"
canonical: "https://docs.infoblox.com/space/NMHIG/35882945/Known%20Limitations"
format: markdown
---
The vNIOS virtual appliance has the following limitations:

- If you configure an HA pair with instances running on a NIOS version prior to 8.6.x, ensure that both nodes in the HA pair are NIOS virtual instances. You cannot configure a physical NIOS appliance and a NIOS virtual instance in an HA pair in versions earlier than 8.6.x.
- vNIOS appliances do not support the configuration of port settings such as speed and duplex for the MGMT, LAN, LAN2, and HA ports.
- vNIOS appliances run on virtual hardware. They do not have sensors to monitor the physical CPU temperature, fan speed, and system temperature.
- When running NIOS in MS Hyper-V with dynamic memory allocation enabled, the system might experience high memory usage. To avoid this issue, Infoblox recommends that you disable dynamic memory allocation.