Merge pull request #220283 from christiankuhtz/patch-331

DHCP clarification

Author: prmerger-automator[bot]

articles/virtual-network/virtual-networks-faq.md

@@ -98,7 +98,10 @@ When NSGs are applied both at NIC & Subnets for a VM, subnet level NSG followed
 No. Multicast and broadcast are not supported.
 
 ### What protocols can I use within VNets?
-You can use TCP, UDP, and ICMP TCP/IP protocols within VNets. Unicast is supported within VNets, with the exception of Dynamic Host Configuration Protocol (DHCP) via Unicast (source port UDP/68 / destination port UDP/67) and UDP source port 65330 which is reserved for the host. Multicast, broadcast, IP-in-IP encapsulated packets, and Generic Routing Encapsulation (GRE) packets are blocked within VNets. 
+You can use TCP, UDP, and ICMP TCP/IP protocols within VNets. Unicast is supported within VNets.  Multicast, broadcast, IP-in-IP encapsulated packets, and Generic Routing Encapsulation (GRE) packets are blocked within VNets. You cannot use Dynamic Host Configuration Protocol (DHCP) via Unicast (source port UDP/68 / destination port UDP/67). UDP source port 65330 which is reserved for the host. See ["Can I deploy a DHCP server in a VNet"](#can-i-deploy-a-dhcp-server-in-a-vnet) for more detail what is and is not supported for DHCP.
+
+### Can I deploy a DHCP server in a VNet?
+Azure VNets provide DHCP service and DNS to VMs and client/server DHCP (source port UDP/68, destination port UDP/67) not supported in a VNet.  You cannot deploy your own DHCP service to receive and provide unicast/broadcast client/server DHCP traffic.  You can deploy a DHCP server on a VM with the intent to receive unicast DHCP relay (source port UDP/67, destination port UDP/67) DHCP traffic.  A possible scenario is configuring DHCP relay from devices on-premises to an Azure VM running a DHCP server. Customer is responsible for configuring on-premise devices (for example, router configuration) to create this DHCP relay traffic to the VM's IP in Azure.
 
 ### Can I ping default gateway within a VNet?
 No. Azure provided default gateway does not respond to ping. But you can use ping in your VNets to check connectivity and troubleshooting between VMs.