Merge branch 'master' of https://github.com/MicrosoftDocs/azure-docs-pr

Author: Sunayana Singh

articles/aks/use-multiple-node-pools.md

@@ -9,7 +9,7 @@ ms.date: 04/08/2020
 
 # Create and manage multiple node pools for a cluster in Azure Kubernetes Service (AKS)
 
-In Azure Kubernetes Service (AKS), nodes of the same configuration are grouped together into *node pools*. These node pools contain the underlying VMs that run your applications. The initial number of nodes and their size (SKU) is defined when you create an AKS cluster, which creates a *default node pool*. To support applications that have different compute or storage demands, you can create additional node pools. For example, use these additional node pools to provide GPUs for compute-intensive applications, or access to high-performance SSD storage.
+In Azure Kubernetes Service (AKS), nodes of the same configuration are grouped together into *node pools*. These node pools contain the underlying VMs that run your applications. The initial number of nodes and their size (SKU) is defined when you create an AKS cluster, which creates a [system node pool][use-system-pool]. To support applications that have different compute or storage demands, you can create additional *user node pools*. System node pools serve the primary purpose of hosting critical system pods such as CoreDNS and tunnelfront. User node pools serve the primary purpose of hosting your application pods. However, application pods can be scheduled on system node pools if you wish to only have one pool in your AKS cluster. User node pools are where you place your application-specific pods. For example, use these additional user node pools to provide GPUs for compute-intensive applications, or access to high-performance SSD storage.
 
 > [!NOTE]
 > This feature enables higher control over how to create and manage multiple node pools. As a result, separate commands are required for  create/update/delete. Previously cluster operations through `az aks create` or `az aks update` used the managedCluster API and were the only option to change your control plane and a single node pool. This feature exposes a separate operation set for agent pools through the agentPool API and require use of the `az aks nodepool` command set to execute operations on an individual node pool.
@@ -25,7 +25,8 @@ You need the Azure CLI version 2.2.0 or later installed and configured. Run `az
 The following limitations apply when you create and manage AKS clusters that support multiple node pools:
 
 * See [Quotas, virtual machine size restrictions, and region availability in Azure Kubernetes Service (AKS)][quotas-skus-regions].
-* You can't delete the system node pool, by default the first node pool.
+* You can delete system node pools, provided you have another system node pool to take its place in the AKS cluster.
+* System pools must contain at least one node, and user node pools may contain zero or more nodes.
 * The AKS cluster must use the Standard SKU load balancer to use multiple node pools, the feature is not supported with Basic SKU load balancers.
 * The AKS cluster must use virtual machine scale sets for the nodes.
 * The name of a node pool may only contain lowercase alphanumeric characters and must begin with a lowercase letter. For Linux node pools the length must be between 1 and 12 characters, for Windows node pools the length must be between 1 and 6 characters.
@@ -34,6 +35,9 @@ The following limitations apply when you create and manage AKS clusters that sup
 
 ## Create an AKS cluster
 
+> [!Important]
+> If you run a single system node pool for your AKS cluster in a production environment, we recommend you use at least three nodes for the node pool.
+
 To get started, create an AKS cluster with a single node pool. The following example uses the [az group create][az-group-create] command to create a resource group named *myResourceGroup* in the *eastus* region. An AKS cluster named *myAKSCluster* is then created using the [az aks create][az-aks-create] command. A *--kubernetes-version* of *1.15.7* is used to show how to update a node pool in a following step. You can specify any [supported Kubernetes version][supported-versions].
 
 > [!NOTE]
@@ -749,6 +753,8 @@ az group delete --name myResourceGroup --yes --no-wait
 
 ## Next steps
 
+Learn more about [system node pools][use-system-pool].
+
 In this article, you learned how to create and manage multiple node pools in an AKS cluster. For more information about how to control pods across node pools, see [Best practices for advanced scheduler features in AKS][operator-best-practices-advanced-scheduler].
 
 To create and use Windows Server container node pools, see [Create a Windows Server container in AKS][aks-windows].
@@ -784,3 +790,4 @@ To create and use Windows Server container node pools, see [Create a Windows Ser
 [tag-limitation]: ../azure-resource-manager/resource-group-using-tags.md
 [taints-tolerations]: operator-best-practices-advanced-scheduler.md#provide-dedicated-nodes-using-taints-and-tolerations
 [vm-sizes]: ../virtual-machines/linux/sizes.md
+[use-system-pool]: use-system-pools.md

articles/aks/use-system-pools.md

@@ -9,7 +9,10 @@ ms.date: 04/06/2020
 
 # Manage system node pools in Azure Kubernetes Service (AKS)
 
-In Azure Kubernetes Service (AKS), nodes of the same configuration are grouped together into *node pools*. Node pools contain the underlying VMs that run your applications. System node pools and user node pools are two different node pool modes for your AKS clusters. System node pools host essential system services such as CoreDNS. User node pools are where you place your application-specific pods. Every AKS cluster must contain at least one system node pool with at least one node. If you run a single system node pool for your AKS cluster, we recommend you use at least three nodes for the node pool. 
+In Azure Kubernetes Service (AKS), nodes of the same configuration are grouped together into *node pools*. Node pools contain the underlying VMs that run your applications. System node pools and user node pools are two different node pool modes for your AKS clusters. System node pools serve the primary purpose of hosting critical system pods such as CoreDNS and tunnelfront. User node pools serve the primary purpose of hosting your application pods. However, application pods can be scheduled on system node pools if you wish to only have one pool in your AKS cluster. Every AKS cluster must contain at least one system node pool with at least one node. 
+
+> [!Important]
+> If you run a single system node pool for your AKS cluster in a production environment, we recommend you use at least three nodes for the node pool.
 
 ## Before you begin
 

articles/search/search-faq-frequently-asked-questions.md

@@ -8,7 +8,7 @@ author: HeidiSteen
 ms.author: heidist
 ms.service: cognitive-search
 ms.topic: conceptual
-ms.date: 11/04/2019
+ms.date: 04/10/2020
 ---
 
 # Azure Cognitive Search - frequently asked questions (FAQ)
@@ -21,16 +21,6 @@ ms.date: 11/04/2019
 
 Azure Cognitive Search supports multiple data sources, [linguistic analysis for many languages](https://docs.microsoft.com/rest/api/searchservice/language-support), [custom analysis for interesting and unusual data inputs](https://docs.microsoft.com/rest/api/searchservice/custom-analyzers-in-azure-search), search rank controls through [scoring profiles](https://docs.microsoft.com/rest/api/searchservice/add-scoring-profiles-to-a-search-index), and user-experience features such as typeahead, hit highlighting, and faceted navigation. It also includes other features, such as synonyms and rich query syntax, but those are generally not differentiating features.
 
-### What is the difference between Azure Cognitive Search and Elasticsearch?
-
-When comparing search technologies, customers frequently ask for specifics on how Azure Cognitive Search compares with Elasticsearch. Customers who choose Azure Cognitive Search over Elasticsearch for their search application projects typically do so because we've made a key task easier or they need the built-in integration with other Microsoft technologies:
-
-+ Azure Cognitive Search is a fully managed cloud service with 99.9% service level agreements (SLA) when provisioned with sufficient redundancy (2 replicas for read access, three replicas for read-write).
-+ Microsoft's [Natural language processors](https://docs.microsoft.com/rest/api/searchservice/language-support) offer leading edge linguistic analysis.  
-+ [Azure Cognitive Search indexers](search-indexer-overview.md) can crawl a variety of Azure data sources for initial and incremental indexing.
-+ If you need rapid response to fluctuations in query or indexing volumes, you can use [slider controls](search-manage.md#scale-up-or-down) in the Azure portal, or run a [PowerShell script](search-manage-powershell.md), bypassing shard management directly.  
-+ [Scoring and tuning features](https://docs.microsoft.com/rest/api/searchservice/add-scoring-profiles-to-a-search-index) provide the means for influencing search rank scores beyond what the search engine alone can provide.
-
 ### Can I pause Azure Cognitive Search service and stop billing?
 
 You cannot pause the service. Computational and storage resources are allocated for your exclusive use when the service is created. It's not possible to release and reclaim those resources on-demand.
@@ -87,7 +77,7 @@ Most wildcard search queries, like prefix, fuzzy and regex, are rewritten intern
 
 By default, search results are scored based on the [statistical properties of matching terms](search-lucene-query-architecture.md#stage-4-scoring), and ordered high to low in the result set. However, some query types (wildcard, prefix, regex) always contribute a constant score to the overall document score. This behavior is by design. Azure Cognitive Search imposes a constant score to allow matches found through query expansion to be included in the results, without affecting the ranking.
 
-For example, suppose an input of "tour*" in a wildcard search produces matches on “tours”, “tourettes”, and “tourmaline”. Given the nature of these results, there is no way to reasonably infer which terms are more valuable than others. For this reason, we ignore term frequencies when scoring results in queries of types wildcard, prefix, and regex. Search results based on a partial input are given a constant score to avoid bias towards potentially unexpected matches.
+For example, suppose an input of "tour*" in a wildcard search produces matches on "tours", "tourettes", and "tourmaline". Given the nature of these results, there is no way to reasonably infer which terms are more valuable than others. For this reason, we ignore term frequencies when scoring results in queries of types wildcard, prefix, and regex. Search results based on a partial input are given a constant score to avoid bias towards potentially unexpected matches.
 
 ## Design patterns
 

articles/virtual-network/virtual-networks-name-resolution-for-vms-and-role-instances.md

@@ -84,6 +84,7 @@ Reverse DNS is supported in all ARM based virtual networks. You can issue revers
 * Forward lookup on FQDNs of form \[vmname\].internal.cloudapp.net will resolve to IP address assigned to the virtual machine.
 * If the virtual network is linked to an [Azure DNS private zones](../dns/private-dns-overview.md) as a registration virtual network, the reverse DNS queries will return two records. One record will the of the form \[vmname\].[priatednszonename] and other would be of the form \[vmname\].internal.cloudapp.net
 * Reverse DNS lookup is scoped to a given virtual network even if it is peered to other virtual networks. Reverse DNS queries (PTR queries) for IP addresses of virtual machines located in peered virtual networks will return NXDOMAIN.
+* If you want to turn off reverse DNS function in a virtual network you can do so by creating a reverse lookup zone using [Azure DNS private zones](../dns/private-dns-overview.md) and link this zone to your virtual network. For example if the IP address space of your virtual network is 10.20.0.0/16 then you can create a empty private DNS zone 20.10.in-addr.arpa and link it to the virtual network. While linking the zone to your virtual network you should disable auto registration on the link. This zone will override the default reverse lookup zones for the virtual network and since this zone is empty you will get NXDOMAIN for your reverse DNS queries. See our [Quickstart guide](https://docs.microsoft.com/azure/dns/private-dns-getstarted-portal) for details on how to create a private DNS zone and link it to a virtual network.
 
 > [!NOTE]
 > If you want reverse DNS lookup to span across virtual network you can create a reverse lookup zone (in-addr.arpa) [Azure DNS private zones](../dns/private-dns-overview.md) and links it to multiple virtual networks. You'll however have to manually manage the reverse DNS records for the virtual machines.
@@ -195,7 +196,7 @@ If you need to perform name resolution from your web app built by using App Serv
 
 * Set up a DNS server in your target virtual network, on a VM that can also forward queries to the recursive resolver in Azure (virtual IP 168.63.129.16). An example DNS forwarder is available in the [Azure Quickstart Templates gallery](https://azure.microsoft.com/documentation/templates/301-dns-forwarder) and [GitHub](https://github.com/Azure/azure-quickstart-templates/tree/master/301-dns-forwarder). 
 * Set up a DNS forwarder in the source virtual network on a VM. Configure this DNS forwarder to forward queries to the DNS server in your target virtual network.
-* Configure your source DNS server in your source virtual network’s settings.
+* Configure your source DNS server in your source virtual network's settings.
 * Enable virtual network integration for your web app to link to the source virtual network, following the instructions in [Integrate your app with a virtual network](../app-service/web-sites-integrate-with-vnet.md?toc=%2fazure%2fvirtual-network%2ftoc.json).
 * In the Azure portal, for the App Service plan hosting the web app, select **Sync Network** under **Networking**, **Virtual Network Integration**.