Merge pull request #184895 from aimee-littleton/patch-16

NAT basics - migrate outbound access

Author: PRMerger18

articles/virtual-network/nat-gateway/nat-overview.md

@@ -37,7 +37,7 @@ NAT will not impact the network bandwidth of your compute resources since it is
 
 ## VNet NAT basics
 
-NAT can be created in a specific Availability Zone and has redundancy built in within the specified zone. NAT is non zonal by default. When creating [availability zones](../../availability-zones/az-overview.md) scenarios, NAT can be isolated in a specific zone. This is known as a zonal deployment.
+NAT can be created in a specific Availability Zone and has redundancy built in within the specified zone. NAT is non-zonal by default. When creating [availability zones](../../availability-zones/az-overview.md) scenarios, NAT can be isolated in a specific zone. This is known as a zonal deployment.
 
 NAT is fully scaled out from the start. There's no ramp up or scale-out operation required.  Azure manages the operation of NAT for you.  NAT always has multiple fault domains and can sustain multiple failures without service outage.
 
@@ -50,9 +50,11 @@ NAT is fully scaled out from the start. There's no ramp up or scale-out operatio
 * NAT is compatible with Standard SKU public IP address or public IP prefix resources or a combination of both. You can use a public IP prefix directly or distribute the public IP addresses of the prefix across multiple NAT gateway resources. NAT will groom all traffic to the range of IP addresses of the prefix. Basic resources, such as Basic Load Balancer or Basic Public IP aren't compatible with NAT.  Basic resources must be placed on a subnet not associated to a NAT Gateway. Basic Load Balancer and Basic Public IP can be upgraded to standard  in order to work with NAT gateway.
   * To upgrade a basic load balancer to standard, see [Upgrade Azure Public Load Balancer](/azure/load-balancer/upgrade-basic-standard)
   * To upgrade a basic public IP to standard, see [Upgrade a public IP address](/azure/virtual-network/ip-services/public-ip-upgrade-portal)
+* NAT is the recommended method for outbound connectivity. A NAT gateway does not have the same limitations of SNAT port exhaustion as does [default outbound access](/azure/virtual-network/ip-services/default-outbound-access) and [outbound rules of a load balancer](/azure/load-balancer/outbound-rules). 
+  * To migrate outbound access to NAT gateway from default outbound access or from outbound rules of a load balancer, see [Migrate outbound access to Azure Virtual Network NAT](/azure/virtual-network/nat-gateway/tutorial-migrate-outbound-nat)
 * NAT cannot be associated to an IPv6 Public IP address or IPv6 Public IP Prefix. However, it can be associated to a dual stack subnet.
 * NAT allows flows to be created from the virtual network to the services outside your VNet. Return traffic from the Internet is only allowed in response to an active flow. Services outside your VNet cannot initiate a connection to instances.
-* NAT can't span multiple virtual networks.
+* NAT cannot span multiple virtual networks.
 * Multiple NATs cannot be attached to a single subnet. 
 * NAT cannot be deployed in a [Gateway Subnet](../../vpn-gateway/vpn-gateway-about-vpn-gateway-settings.md#gwsub)
 * The private side of NAT (virtual machine instances or other compute resources) sends TCP Reset packets for attempts to communicate on a TCP connection that doesn't exist. One example is connections that have reached idle timeout. The next packet received will return a TCP Reset to the private IP address to signal and force connection closure. The public side of NAT doesn't generate TCP Reset packets or any other traffic.  Only traffic produced by the customer's virtual network is emitted.