{"id":2455,"date":"2018-02-07T21:43:37","date_gmt":"2018-02-07T21:43:37","guid":{"rendered":"http:\/\/microsoftgeek.com\/?p=2455"},"modified":"2018-02-07T21:44:22","modified_gmt":"2018-02-07T21:44:22","slug":"getting-started-with-exchange-server-2010-client-access-server-arrays","status":"publish","type":"post","link":"https:\/\/microsoftgeek.com\/?p=2455","title":{"rendered":"Getting Started with Exchange Server 2010 Client Access Server Arrays"},"content":{"rendered":"<p>An often misunderstood feature of\u00a0Exchange Server 2010\u00a0is the Client Access server array, or CAS array.<\/p>\n<p>In Exchange Server 2007 the Client Access server role was introduced to perform a similar role to the Exchange 2003 Front-End server, in that it was responsible for accepting client connections for services such as Outlook Web Access, ActiveSync, Outlook Anywhere, and other web services. However a mailbox user still connected directly to the Exchange 2007 Mailbox server for mailbox and public folder access.<\/p>\n<figure id=\"attachment_4532\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-4532\" title=\"exchange-2007-client-access-server\" src=\"https:\/\/practical365.com\/wp-content\/uploads\/2012\/02\/exchange-2007-client-access-server1.png\" alt=\"Exchange 2007 Client Access server\" width=\"571\" height=\"258\" \/><figcaption class=\"wp-caption-text\">Exchange 2007 Client Access server<\/figcaption><\/figure>\n<p>In Exchange Server 2010 the\u00a0Client Access server role\u00a0was expanded to include a new service called the RPC Client Access Service. This service allows Outlook clients to connect via MAPI\/RPC to the Client Access server for mailbox access, however they do still connect directly to mailbox servers for public folder access.<\/p>\n<figure id=\"attachment_4529\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-4529\" title=\"exchange-2010-client-access-server\" src=\"https:\/\/practical365.com\/wp-content\/uploads\/2012\/02\/exchange-2010-client-access-server.png\" alt=\"Exchange 2010 Client Access server role\" width=\"571\" height=\"184\" \/><figcaption class=\"wp-caption-text\">Exchange 2010 Client Access server role<\/figcaption><\/figure>\n<p>This new RPC Client Access service delivers several benefits to the organization:<\/p>\n<ul>\n<li>Connections to mailbox resources are made via a common path<\/li>\n<li>Connection throttling and other rules can be applied to mailbox connectivity<\/li>\n<li>The end user experience during\u00a0Mailbox server failovers\u00a0and mailbox moves is improved<\/li>\n<li>The RPC Client Access service can be made\u00a0highly available<\/li>\n<\/ul>\n<h2>Basic Requirements of a Client Access Server Array<\/h2>\n<p>Although a CAS array is often assumed to be highly available, it is important to realise that it is not the Client Access Server array itself that delivers high availability.<\/p>\n<p>The Client Access Server array is simply an object in Active Directory that associates a DNS name with the RPC Client Access Service for a particular AD Site.<\/p>\n<p>Therefore to create a CAS array you only need to:<\/p>\n<ol>\n<li>Create the CAS Array object in Active Directory<\/li>\n<li>Configure a DNS record for the CAS Array name pointing to an IP address for a Client Access server<\/li>\n<li>Configure the RPCClientAccessServer attribute on the mailbox databases in that site<\/li>\n<\/ol>\n<h3>Creating a Client Access Server Array<\/h3>\n<p>CAS Array objects are created using the Exchange Management Shell and the\u00a0New-ClientAccessArray\u00a0cmdlet. In this example a CAS Array is created with:<\/p>\n<ul>\n<li>a name of \u201ccas-headoffice\u201d<\/li>\n<li>a FQDN of \u201coutlook-ho.exchangeserverpro.net\u201d<\/li>\n<li>the AD Site of \u201cHeadOffice\u201d<\/li>\n<\/ul>\n<div id=\"crayon-5a7b7253a6e22123926335\" class=\"crayon-syntax crayon-theme-powershell-custom crayon-font-consolas crayon-os-pc print-yes notranslate\" data-settings=\" minimize scroll-always\">\n<div class=\"crayon-toolbar\" data-settings=\" show\"><\/div>\n<div class=\"crayon-plain-wrap\"><\/div>\n<div class=\"crayon-main\">\n<table class=\"crayon-table\">\n<tbody>\n<tr class=\"crayon-row\">\n<td class=\"crayon-nums \" data-settings=\"hide\">\n<div class=\"crayon-nums-content\">\n<div class=\"crayon-num\" data-line=\"crayon-5a7b7253a6e22123926335-1\">1<\/div>\n<div class=\"crayon-num crayon-striped-num\" data-line=\"crayon-5a7b7253a6e22123926335-2\">2<\/div>\n<div class=\"crayon-num\" data-line=\"crayon-5a7b7253a6e22123926335-3\">3<\/div>\n<div class=\"crayon-num crayon-striped-num\" data-line=\"crayon-5a7b7253a6e22123926335-4\">4<\/div>\n<div class=\"crayon-num\" data-line=\"crayon-5a7b7253a6e22123926335-5\">5<\/div>\n<\/div>\n<\/td>\n<td class=\"crayon-code\">\n<div class=\"crayon-pre\">\n<div id=\"crayon-5a7b7253a6e22123926335-1\" class=\"crayon-line\"><span class=\"crayon-sy\">[<\/span><span class=\"crayon-v\">PS<\/span><span class=\"crayon-sy\">]<\/span> <span class=\"crayon-v\">C<\/span><span class=\"crayon-o\">:<\/span><span class=\"crayon-sy\">\\<\/span><span class=\"crayon-o\">&gt;<\/span><span class=\"crayon-r\">New<\/span><span class=\"crayon-o\">&#8211;<\/span><span class=\"crayon-v\">ClientAccessArray<\/span> <span class=\"crayon-o\">&#8211;<\/span><span class=\"crayon-e\">Name <\/span><span class=\"crayon-v\">cas<\/span><span class=\"crayon-o\">&#8211;<\/span><span class=\"crayon-v\">headoffice<\/span> <span class=\"crayon-o\">&#8211;<\/span><span class=\"crayon-e\">Fqdn <\/span><span class=\"crayon-v\">outlook<\/span><span class=\"crayon-o\">&#8211;<\/span><span class=\"crayon-v\">ho<\/span><span class=\"crayon-sy\">.<\/span><span class=\"crayon-v\">exchangeserverpro<\/span><span class=\"crayon-sy\">.<\/span><span class=\"crayon-v\">net<\/span> <span class=\"crayon-o\">&#8211;<\/span><span class=\"crayon-e\">Site <\/span><span class=\"crayon-e\">HeadOffice<\/span><\/div>\n<div id=\"crayon-5a7b7253a6e22123926335-2\" class=\"crayon-line crayon-striped-line\"><\/div>\n<div id=\"crayon-5a7b7253a6e22123926335-3\" class=\"crayon-line\"><span class=\"crayon-e\">Name\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><span class=\"crayon-e\">Site\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/span><span class=\"crayon-e\">Fqdn\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/span><span class=\"crayon-v\">Members<\/span><\/div>\n<div id=\"crayon-5a7b7253a6e22123926335-4\" class=\"crayon-line crayon-striped-line\"><span class=\"crayon-o\">&#8212;<\/span><span class=\"crayon-o\">&#8212;<\/span><span class=\"crayon-h\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><span class=\"crayon-o\">&#8212;<\/span><span class=\"crayon-o\">&#8212;<\/span><span class=\"crayon-h\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/span><span class=\"crayon-o\">&#8212;<\/span><span class=\"crayon-o\">&#8212;<\/span><span class=\"crayon-h\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/span><span class=\"crayon-o\">&#8212;<\/span><span class=\"crayon-o\">&#8212;<\/span><span class=\"crayon-o\">&#8212;<\/span><span class=\"crayon-o\">&#8211;<\/span><\/div>\n<div id=\"crayon-5a7b7253a6e22123926335-5\" class=\"crayon-line\"><span class=\"crayon-v\">cas<\/span><span class=\"crayon-o\">&#8211;<\/span><span class=\"crayon-e\">headoffice\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><span class=\"crayon-e\">HeadOffice\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 <\/span><span class=\"crayon-v\">outlook<\/span><span class=\"crayon-o\">&#8211;<\/span><span class=\"crayon-v\">ho<\/span><span class=\"crayon-sy\">.<\/span><span class=\"crayon-v\">exchangeserverpr<\/span><span class=\"crayon-sy\">.<\/span><span class=\"crayon-sy\">.<\/span><span class=\"crayon-sy\">.<\/span> <span class=\"crayon-sy\">{<\/span><span class=\"crayon-v\">HO<\/span><span class=\"crayon-o\">&#8211;<\/span><span class=\"crayon-v\">EX2010<\/span><span class=\"crayon-o\">&#8211;<\/span><span class=\"crayon-v\">MB1<\/span><span class=\"crayon-sy\">,<\/span> <span class=\"crayon-v\">HO<\/span><span class=\"crayon-o\">&#8211;<\/span><span class=\"crayon-v\">EX2010<\/span><span class=\"crayon-o\">&#8211;<\/span><span class=\"crayon-v\">MB2<\/span><span class=\"crayon-sy\">}<\/span><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n<p>If you are running a single AD Site in your organization the CAS Array name and FQDN can be anything you like, however if you&#8217;re running multiple sites then you will need to put some thought into a naming standard for your CAS Arrays so that each one is unique.<\/p>\n<h3>Configuring the DNS Record for the Client Access Server Array<\/h3>\n<p>The next step is to configure a DNS A record for the FQDN you specified when creating the CAS Array object.<\/p>\n<figure id=\"attachment_4534\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-4534\" title=\"exchange-2010-cas-array-dns-record\" src=\"https:\/\/practical365.com\/wp-content\/uploads\/2012\/02\/exchange-2010-cas-array-dns-record.jpg\" alt=\"DNS A record for the Exchange 2010 CAS Array\" width=\"404\" height=\"251\" \/><figcaption class=\"wp-caption-text\">DNS A record for the Exchange 2010 CAS Array<\/figcaption><\/figure>\n<h3>Configure the RPCClientAccessServer Attribute on Mailbox Databases<\/h3>\n<p>The final step is to configure the mailbox databases with the correct RPCClientAccessServer attribute. It is this attribute that Outlook looks up to determine which RPC Client Access Server to connect to for a given mailbox.<\/p>\n<p>The attribute is set automatically when the mailbox database is created to either:<\/p>\n<ul>\n<li>The CAS Array name if one already exists in the AD Site<\/li>\n<li>The FQDN of a Client Access server in the AD Site<\/li>\n<\/ul>\n<p>You can see from this that it is wise to configure the CAS Array object first before creating mailbox databases, or at the very least creating the CAS Array object and updating the mailbox databases before deploying mailbox users to those databases.<\/p>\n<p>You can check the existing settings by running the\u00a0Get-MailboxDatabase\u00a0cmdlet.<\/p>\n<div id=\"crayon-5a7b7253a6e2f881188627\" class=\"crayon-syntax crayon-theme-powershell-custom crayon-font-consolas crayon-os-pc print-yes notranslate\" data-settings=\" minimize scroll-always\">\n<div class=\"crayon-toolbar\" data-settings=\" show\"><\/div>\n<div class=\"crayon-plain-wrap\"><\/div>\n<div class=\"crayon-main\">\n<table class=\"crayon-table\">\n<tbody>\n<tr class=\"crayon-row\">\n<td class=\"crayon-nums \" data-settings=\"hide\">\n<div class=\"crayon-nums-content\">\n<div class=\"crayon-num\" data-line=\"crayon-5a7b7253a6e2f881188627-1\">1<\/div>\n<div class=\"crayon-num crayon-striped-num\" data-line=\"crayon-5a7b7253a6e2f881188627-2\">2<\/div>\n<div class=\"crayon-num\" data-line=\"crayon-5a7b7253a6e2f881188627-3\">3<\/div>\n<div class=\"crayon-num crayon-striped-num\" data-line=\"crayon-5a7b7253a6e2f881188627-4\">4<\/div>\n<div class=\"crayon-num\" data-line=\"crayon-5a7b7253a6e2f881188627-5\">5<\/div>\n<div class=\"crayon-num crayon-striped-num\" data-line=\"crayon-5a7b7253a6e2f881188627-6\">6<\/div>\n<div class=\"crayon-num\" data-line=\"crayon-5a7b7253a6e2f881188627-7\">7<\/div>\n<div class=\"crayon-num crayon-striped-num\" data-line=\"crayon-5a7b7253a6e2f881188627-8\">8<\/div>\n<div class=\"crayon-num\" data-line=\"crayon-5a7b7253a6e2f881188627-9\">9<\/div>\n<\/div>\n<\/td>\n<td class=\"crayon-code\">\n<div class=\"crayon-pre\">\n<div id=\"crayon-5a7b7253a6e2f881188627-1\" class=\"crayon-line\"><span class=\"crayon-sy\">[<\/span><span class=\"crayon-v\">PS<\/span><span class=\"crayon-sy\">]<\/span> <span class=\"crayon-v\">C<\/span><span class=\"crayon-o\">:<\/span><span class=\"crayon-sy\">\\<\/span><span class=\"crayon-o\">&gt;<\/span><span class=\"crayon-v\">Get<\/span><span class=\"crayon-o\">&#8211;<\/span><span class=\"crayon-v\">MailboxDatabase<\/span> <span class=\"crayon-o\">|<\/span> <span class=\"crayon-e\">select <\/span><span class=\"crayon-v\">name<\/span><span class=\"crayon-sy\">,<\/span><span class=\"crayon-v\">rpcclientaccessserver<\/span> <span class=\"crayon-o\">|<\/span> <span class=\"crayon-v\">ft<\/span> <span class=\"crayon-o\">&#8211;<\/span><span class=\"crayon-e\">auto<\/span><\/div>\n<div id=\"crayon-5a7b7253a6e2f881188627-2\" class=\"crayon-line crayon-striped-line\"><\/div>\n<div id=\"crayon-5a7b7253a6e2f881188627-3\" class=\"crayon-line\"><span class=\"crayon-e\">Name\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><span class=\"crayon-v\">RpcClientAccessServer<\/span><\/div>\n<div id=\"crayon-5a7b7253a6e2f881188627-4\" class=\"crayon-line crayon-striped-line\"><span class=\"crayon-o\">&#8212;<\/span><span class=\"crayon-o\">&#8212;<\/span><span class=\"crayon-h\">\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><span class=\"crayon-o\">&#8212;<\/span><span class=\"crayon-o\">&#8212;<\/span><span class=\"crayon-o\">&#8212;<\/span><span class=\"crayon-o\">&#8212;<\/span><span class=\"crayon-o\">&#8212;<\/span><span class=\"crayon-o\">&#8212;<\/span><span class=\"crayon-o\">&#8212;<\/span><span class=\"crayon-o\">&#8212;<\/span><span class=\"crayon-o\">&#8212;<\/span><span class=\"crayon-o\">&#8212;<\/span><span class=\"crayon-o\">&#8211;<\/span><\/div>\n<div id=\"crayon-5a7b7253a6e2f881188627-5\" class=\"crayon-line\"><span class=\"crayon-v\">MB<\/span><span class=\"crayon-o\">&#8211;<\/span><span class=\"crayon-v\">HO<\/span><span class=\"crayon-o\">&#8211;<\/span><span class=\"crayon-cn\">01<\/span><span class=\"crayon-h\">\u00a0\u00a0<\/span><span class=\"crayon-v\">HO<\/span><span class=\"crayon-o\">&#8211;<\/span><span class=\"crayon-v\">EX2010<\/span><span class=\"crayon-o\">&#8211;<\/span><span class=\"crayon-v\">MB1<\/span><span class=\"crayon-sy\">.<\/span><span class=\"crayon-v\">exchangeserverpro<\/span><span class=\"crayon-sy\">.<\/span><span class=\"crayon-e\">net<\/span><\/div>\n<div id=\"crayon-5a7b7253a6e2f881188627-6\" class=\"crayon-line crayon-striped-line\"><span class=\"crayon-v\">MB<\/span><span class=\"crayon-o\">&#8211;<\/span><span class=\"crayon-v\">HO<\/span><span class=\"crayon-o\">&#8211;<\/span><span class=\"crayon-cn\">02<\/span><span class=\"crayon-h\">\u00a0\u00a0<\/span><span class=\"crayon-v\">HO<\/span><span class=\"crayon-o\">&#8211;<\/span><span class=\"crayon-v\">EX2010<\/span><span class=\"crayon-o\">&#8211;<\/span><span class=\"crayon-v\">MB1<\/span><span class=\"crayon-sy\">.<\/span><span class=\"crayon-v\">exchangeserverpro<\/span><span class=\"crayon-sy\">.<\/span><span class=\"crayon-e\">net<\/span><\/div>\n<div id=\"crayon-5a7b7253a6e2f881188627-7\" class=\"crayon-line\"><span class=\"crayon-v\">MB<\/span><span class=\"crayon-o\">&#8211;<\/span><span class=\"crayon-v\">BR<\/span><span class=\"crayon-o\">&#8211;<\/span><span class=\"crayon-cn\">01<\/span><span class=\"crayon-h\">\u00a0\u00a0<\/span><span class=\"crayon-v\">BR<\/span><span class=\"crayon-o\">&#8211;<\/span><span class=\"crayon-v\">EX2010<\/span><span class=\"crayon-o\">&#8211;<\/span><span class=\"crayon-v\">MB<\/span><span class=\"crayon-sy\">.<\/span><span class=\"crayon-v\">exchangeserverpro<\/span><span class=\"crayon-sy\">.<\/span><span class=\"crayon-e\">net<\/span><\/div>\n<div id=\"crayon-5a7b7253a6e2f881188627-8\" class=\"crayon-line crayon-striped-line\"><span class=\"crayon-v\">MB<\/span><span class=\"crayon-o\">&#8211;<\/span><span class=\"crayon-v\">HO<\/span><span class=\"crayon-o\">&#8211;<\/span><span class=\"crayon-cn\">03<\/span><span class=\"crayon-h\">\u00a0\u00a0<\/span><span class=\"crayon-v\">HO<\/span><span class=\"crayon-o\">&#8211;<\/span><span class=\"crayon-v\">EX2010<\/span><span class=\"crayon-o\">&#8211;<\/span><span class=\"crayon-v\">MB1<\/span><span class=\"crayon-sy\">.<\/span><span class=\"crayon-v\">exchangeserverpro<\/span><span class=\"crayon-sy\">.<\/span><span class=\"crayon-e\">net<\/span><\/div>\n<div id=\"crayon-5a7b7253a6e2f881188627-9\" class=\"crayon-line\"><span class=\"crayon-v\">RDB<\/span><span class=\"crayon-o\">&#8211;<\/span><span class=\"crayon-v\">HO<\/span><span class=\"crayon-o\">&#8211;<\/span><span class=\"crayon-cn\">01<\/span> <span class=\"crayon-v\">HO<\/span><span class=\"crayon-o\">&#8211;<\/span><span class=\"crayon-v\">EX2010<\/span><span class=\"crayon-o\">&#8211;<\/span><span class=\"crayon-v\">MB1<\/span><span class=\"crayon-sy\">.<\/span><span class=\"crayon-v\">exchangeserverpro<\/span><span class=\"crayon-sy\">.<\/span><span class=\"crayon-v\">net<\/span><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n<p>To update the RPCClientAccessServer attribute for a mailbox database run the\u00a0Set-MailboxDatabase\u00a0cmdlet.<\/p>\n<div id=\"crayon-5a7b7253a6e33673561976\" class=\"crayon-syntax crayon-theme-powershell-custom crayon-font-consolas crayon-os-pc print-yes notranslate\" data-settings=\" minimize scroll-always\">\n<div class=\"crayon-toolbar\" data-settings=\" show\"><\/div>\n<div class=\"crayon-plain-wrap\"><\/div>\n<div class=\"crayon-main\">\n<table class=\"crayon-table\">\n<tbody>\n<tr class=\"crayon-row\">\n<td class=\"crayon-nums \" data-settings=\"hide\">\n<div class=\"crayon-nums-content\">\n<div class=\"crayon-num\" data-line=\"crayon-5a7b7253a6e33673561976-1\">1<\/div>\n<\/div>\n<\/td>\n<td class=\"crayon-code\">\n<div class=\"crayon-pre\">\n<div id=\"crayon-5a7b7253a6e33673561976-1\" class=\"crayon-line\"><span class=\"crayon-sy\">[<\/span><span class=\"crayon-v\">PS<\/span><span class=\"crayon-sy\">]<\/span> <span class=\"crayon-v\">C<\/span><span class=\"crayon-o\">:<\/span><span class=\"crayon-sy\">\\<\/span><span class=\"crayon-o\">&gt;<\/span><span class=\"crayon-v\">Set<\/span><span class=\"crayon-o\">&#8211;<\/span><span class=\"crayon-e\">MailboxDatabase <\/span><span class=\"crayon-v\">MB<\/span><span class=\"crayon-o\">&#8211;<\/span><span class=\"crayon-v\">HO<\/span><span class=\"crayon-o\">&#8211;<\/span><span class=\"crayon-cn\">01<\/span> <span class=\"crayon-o\">&#8211;<\/span><span class=\"crayon-e\">RpcClientAccessServer <\/span><span class=\"crayon-v\">outlook<\/span><span class=\"crayon-o\">&#8211;<\/span><span class=\"crayon-v\">ho<\/span><span class=\"crayon-sy\">.<\/span><span class=\"crayon-v\">exchangeserverpro<\/span><span class=\"crayon-sy\">.<\/span><span class=\"crayon-v\">net<\/span><\/div>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n<h2>High Availability for Exchange 2010 Client Access Server Arrays<\/h2>\n<p>As I mentioned earlier one of the benefits of the CAS Array is that is enables the RPC Client Access Server service to be made highly available.<\/p>\n<p>The configuration of the CAS Array itself is the same, however instead of pointing the DNS record at the IP address of a single Client Access server you would point it at the virtual IP of a load balanced array of servers.<\/p>\n<figure id=\"attachment_4535\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-4535\" title=\"exchange-2010-load-balancer\" src=\"https:\/\/practical365.com\/wp-content\/uploads\/2012\/02\/exchange-2010-load-balancer.png\" alt=\"Exchange 2010 load balanced CAS Array\" width=\"598\" height=\"282\" \/><\/figure>\n<p>The load balancing can be achieved in multiple ways:<\/p>\n<ul>\n<li>By deploying a\u00a0Windows Network Load Balancing (NLB) cluster\u00a0for the Client Access Servers<\/li>\n<li>By deploying a virtual or hardware-based load balancer appliance<\/li>\n<\/ul>\n<h2>Best Practices for Exchange Server 2010 CAS Arrays<\/h2>\n<p>Because of the behaviour of the mailbox databases and their RPCClientAccessServer attributes, and how this is handled by different Outlook versions, it is considered best<\/p>\n<p>practice to:<\/p>\n<ul>\n<li>Always configure CAS Arrays in your Exchange 2010 sites<\/li>\n<li>Configure the CAS Array before you provision mailbox databases or mailbox users to Exchange 2010 in that site<\/li>\n<\/ul>\n<p>Microsoft themselves\u00a0<a href=\"https:\/\/technet.microsoft.com\/en-us\/library\/ee332317(v=exchg.141).aspx#CASarray\">recommend this<\/a>\u00a0as a best practice.<\/p>\n<blockquote><p>We recommend that you create a Client Access server array even if you only have a single Client Access server within your organization.<\/p><\/blockquote>\n<p>This has several benefits, such as:<\/p>\n<ul>\n<li>making it easy to scale out the CAS Array name to multiple Exchange 2010 Client Access servers<\/li>\n<li>making it simpler to replace a Client Access server with a new one of a different name<\/li>\n<li>migrating the MAPI endpoint to future versions of Exchange Server<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>An often misunderstood feature of\u00a0Exchange Server 2010\u00a0is the Client Access server array, or CAS array. In Exchange Server 2007 the Client Access server role was introduced to perform a similar role to the Exchange 2003 Front-End server, in that it was responsible for accepting client connections for services such as Outlook Web Access, ActiveSync, Outlook [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[22],"tags":[],"class_list":["post-2455","post","type-post","status-publish","format-standard","hentry","category-exchange-2010"],"_links":{"self":[{"href":"https:\/\/microsoftgeek.com\/index.php?rest_route=\/wp\/v2\/posts\/2455","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/microsoftgeek.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/microsoftgeek.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/microsoftgeek.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/microsoftgeek.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=2455"}],"version-history":[{"count":2,"href":"https:\/\/microsoftgeek.com\/index.php?rest_route=\/wp\/v2\/posts\/2455\/revisions"}],"predecessor-version":[{"id":2457,"href":"https:\/\/microsoftgeek.com\/index.php?rest_route=\/wp\/v2\/posts\/2455\/revisions\/2457"}],"wp:attachment":[{"href":"https:\/\/microsoftgeek.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=2455"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/microsoftgeek.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=2455"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/microsoftgeek.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=2455"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}