Merge pull request #210022 from b-branco/dns-bug-fix

prmerger-automator[bot] · web-flow · commit 3d4de9a8d372 · 2022-09-14T13:24:16.000Z
Stronger advice for configuring DNS
diff --git a/articles/private-5g-core/collect-required-information-for-a-site.md b/articles/private-5g-core/collect-required-information-for-a-site.md
@@ -72,7 +72,7 @@ Collect all the values in the following table to define the packet core instance
    |The data subnet default gateway. You identified this in [Allocate subnets and IP addresses](complete-private-mobile-network-prerequisites.md#allocate-subnets-and-ip-addresses) and it must match the value you used when deploying the AKS-HCI cluster.                               | **N6 gateway** (for 5G) or **SGi gateway** (for 4G). |
    | The network address of the subnet from which dynamic IP addresses must be allocated to user equipment (UEs), given in CIDR notation. You won't need this address if you don't want to support dynamic IP address allocation for this site. You identified this in [Allocate user equipment (UE) IP address pools](complete-private-mobile-network-prerequisites.md#allocate-user-equipment-ue-ip-address-pools). The following example shows the network address format. </br></br>`198.51.100.0/24` </br></br>Note that the UE subnets aren't related to the access subnet.    |**Dynamic UE IP pool prefixes**|
    | The network address of the subnet from which static IP addresses must be allocated to user equipment (UEs), given in CIDR notation. You won't need this address if you don't want to support static IP address allocation for this site. You identified this in [Allocate user equipment (UE) IP address pools](complete-private-mobile-network-prerequisites.md#allocate-user-equipment-ue-ip-address-pools). The following example shows the network address format. </br></br>`198.51.100.0/24` </br></br>Note that the UE subnets aren't related to the access subnet.    |**Static UE IP pool prefixes**|
-   | The Domain Name System (DNS) server addresses to be provided to the UEs connected to this data network. You identified this in [Allocate subnets and IP addresses](complete-private-mobile-network-prerequisites.md#allocate-subnets-and-ip-addresses). We recommend that you collect these addresses to allow the UEs to resolve domain names. </br></br>This value may be an empty list if you don't want to configure a DNS server for the data network (for example, if you want to use this data network for local [UE-to-UE traffic](private-5g-core-overview.md#ue-to-ue-traffic) only). | **DNS Addresses** |
+   | The Domain Name System (DNS) server addresses to be provided to the UEs connected to this data network. You identified this in [Allocate subnets and IP addresses](complete-private-mobile-network-prerequisites.md#allocate-subnets-and-ip-addresses). You must collect these addresses to allow the UEs to resolve domain names. </br></br>This value may be an empty list if you don't want to configure a DNS server for the data network. In this case, UEs in this data network will be unable to access the public internet. | **DNS Addresses** |
    |Whether Network Address and Port Translation (NAPT) should be enabled for this data network. NAPT allows you to translate a large pool of private IP addresses for UEs to a small number of public IP addresses. The translation is performed at the point where traffic enters the data network, maximizing the utility of a limited supply of public IP addresses.</br></br>If you want to use [UE-to-UE traffic](private-5g-core-overview.md#ue-to-ue-traffic) in this data network, keep NAPT disabled.  |**NAPT**|
 
 ## Next steps
diff --git a/articles/private-5g-core/complete-private-mobile-network-prerequisites.md b/articles/private-5g-core/complete-private-mobile-network-prerequisites.md
@@ -52,7 +52,6 @@ For each of these networks, allocate a subnet and then identify the listed IP ad
 - Default gateway.
 - One IP address for port 6 on the Azure Stack Edge Pro device.
 - One IP address for the user plane interface. For 5G, this interface is the N6 interface, whereas for 4G, it's the SGi interface.
-- Optionally, one or more Domain Name System (DNS) server addresses.
 
 ## Allocate user equipment (UE) IP address pools
 
@@ -73,6 +72,16 @@ For each site you're deploying, do the following:
 
 - Decide whether you want to enable Network Address and Port Translation (NAPT) for the data network. NAPT allows you to translate a large pool of private IP addresses for UEs to a small number of public IP addresses. The translation is performed at the point where traffic enters the data network, maximizing the utility of a limited supply of public IP addresses.
 
+## Configure Domain Name System (DNS) servers
+
+> [!IMPORTANT]
+> If you don't configure DNS servers for a data network, all UEs using that network will be unable to resolve domain names and access the public internet.
+
+DNS allows the translation between human-readable domain names and their associated machine-readable IP addresses. Depending on your requirements, you have the following options for configuring a DNS server for your data network:
+
+- If you need the UEs connected to this data network to resolve domain names, you must configure one or more DNS servers. You must use a private DNS server if you need DNS resolution of internal hostnames. If you're only providing internet access to public DNS names, you can use a public or private DNS server.
+- If you don't need the UEs to perform DNS resolution, or if all UEs in the network will use their own locally configured DNS servers (instead of the DNS servers signalled to them by the packet core), you can omit this configuration.
+
 ## Prepare your networks
 
 For each site you're deploying, do the following. 
diff --git a/articles/private-5g-core/create-site-arm-template.md b/articles/private-5g-core/create-site-arm-template.md
@@ -73,7 +73,7 @@ Four Azure resources are defined in the template.
     |**User Equipment Static Address Pool Prefix**  | Enter the network address of the subnet from which static IP addresses must be allocated to User Equipment (UEs) in CIDR notation. You can omit this if you don't want to support static IP address allocation. |
     | **Core Network Technology** | Enter *5GC* for 5G, or *EPC* for 4G. |
     | **Napt Enabled** | Set this field depending on whether Network Address and Port Translation (NAPT) should be enabled for the data network. |
-    | **Dns Addresses** | Enter the DNS server addresses. You can omit this if you don't want to configure a DNS server for the UEs in this data network. |
+    | **Dns Addresses** | Enter the DNS server addresses. You should only omit this if the UEs in this data network don't need to access the public internet. |
     | **Custom Location** | Enter the resource ID of the custom location that targets the Azure Kubernetes Service on Azure Stack HCI (AKS-HCI) cluster on the Azure Stack Edge Pro device in the site. |
 
 1. Select **Review + create**.
diff --git a/articles/private-5g-core/deploy-private-mobile-network-with-site-arm-template.md b/articles/private-5g-core/deploy-private-mobile-network-with-site-arm-template.md
@@ -94,7 +94,7 @@ The following Azure resources are defined in the template.
     |**Data Network Name**  | Enter the name of the data network. |    
     |**Core Network Technology**  | Enter *5GC* for 5G, or *EPC* for 4G. |
     |**Napt Enabled** | Set this field depending on whether Network Address and Port Translation (NAPT) should be enabled for the data network.|
-    | **Dns Addresses** | Enter the DNS server addresses. You can omit this if you don't want to configure a DNS server for the UEs in this data network. |
+    | **Dns Addresses** | Enter the DNS server addresses. You should only omit this if the UEs in this data network don't need to access the public internet. |
     |**Custom Location** | Enter the resource ID of the custom location that targets the Azure Kubernetes Service on Azure Stack HCI (AKS-HCI) cluster on the Azure Stack Edge Pro device in the site.|    
 
 1. Select **Review + create**.
