Merge pull request #307794 from siddomala/arsFAQ

Updated ARS FAQ

Author: prmerger-automator[bot]

articles/route-server/route-server-faq.md

@@ -53,6 +53,12 @@ No. If you deploy a virtual network with an IPv6 address space and later deploy
 
 You can peer a virtual network with an IPv6 address space to Route Server's virtual network, and IPv4 connectivity with this peered dual-stack virtual network continues to function. IPv6 connectivity with this peered virtual network isn't supported. 
 
+### What are routing infrastructure units?
+
+By default, an Azure Route Server is deployed with a capacity of two routing infrastructure units. This default deployment supports 4,000 connected VMs deployed in Route Server's virtual network and all peered virtual networks. 
+
+You can specify more routing infrastructure units to increase Route Server's capacity in increments of 1,000 VMs. Each additional routing infrastructure unit costs $0.10/hour.
+
 
 ## Routing