{"id":4359,"date":"2013-01-07T00:01:00","date_gmt":"2013-01-07T00:01:00","guid":{"rendered":"https:\/\/blogs.technet.microsoft.com\/heyscriptingguy\/2013\/01\/07\/use-powershell-to-troubleshoot-client-dns\/"},"modified":"2013-01-07T00:01:00","modified_gmt":"2013-01-07T00:01:00","slug":"use-powershell-to-troubleshoot-client-dns","status":"publish","type":"post","link":"https:\/\/devblogs.microsoft.com\/scripting\/use-powershell-to-troubleshoot-client-dns\/","title":{"rendered":"Use PowerShell to Troubleshoot Client DNS"},"content":{"rendered":"

Summary:<\/strong> Microsoft Scripting Guy, Ed Wilson, talks about using Windows PowerShell to troubleshoot client DNS.\nMicrosoft Scripting Guy, Ed Wilson, is here. It seems that when I travel invariably at some point on the trip I end up in a hotel that has DNS issues.\nIn the past, that meant opening up the CMD prompt and typing a bunch of cryptic commands. Not anymore. On my Windows 8 laptop (and even on my Windows Surface RT), I can use functions from the dnsclient module to do my troubleshooting.\nOf course, with Windows PowerShell 3.0 (which comes on Windows 8, Windows Surface, and Windows Server 2012) knowing what module contains what function (or cmdlet) is not required.<\/p>\n

Viewing the DNS client settings<\/h2>\n

If I am experiencing connectivity issues, and I suspect a DNS issue, one of the first things I do is check to see what DNS server my device uses. To find this information, I use the Get-DNSClient<\/strong> function. This command is shown here.<\/p>\n

19:09 C:> Get-DnsClient<\/p>\n

 InterfaceAlias     Interface ConnectionSpecificSuffix ConnectionSpecificSuffixSearchList<\/p>\n

————–               ——— ———————— ——————–<\/p>\n

Local Area Connection* 14           33                          {}<\/p>\n

vEthernet (WirelessSwitch)          31 owv.atl.wayport.net      {}<\/p>\n

isatap.owv.atl.wayport.net          44 owv.atl.wayport.net      {}<\/p>\n

Local Area Connection* 12           25                          {}<\/p>\n

vEthernet (InternalSwitch)          19                          {}<\/p>\n

isatap.{FC2087E9-6988-45E…        40                          {}<\/p>\n

Loopback Pseudo-Interface 1          1                          {}<\/p>\n

Teredo Tunneling Pseudo-I…        34                          {}<\/p>\n

6TO4 Adapter                        39                          {}\n \nThe preceding output is a bit much. In fact, it is too much to read. One easy way to filter the output is to display only the connections that have a connection suffix. This command is shown here.<\/p>\n

19:09 C:> Get-DnsClient | ? connectionspecificsuffix<\/p>\n

InterfaceAlias               Interface ConnectionSpecificSuffix ConnectionSpecificSuffixSearchList<\/p>\n

————–               ——— ———————— ——————–<\/p>\n

vEthernet (WirelessSwitch)          31 owv.atl.wayport.net      {}<\/p>\n

isatap.owv.atl.wayport.net          44 owv.atl.wayport.net      {}\n \nIf I want to see the network adapters associated with the particular network interface, I pipe the results to the Get-NetAdapter<\/strong> function. This command is shown here.<\/p>\n

Note<\/strong>   Interface 44 does not exist on my laptop and an error appears. To avoid the errors, specify an erroraction of 0.<\/p>\n

19:10 C:> Get-DnsClient | ? connectionspecificsuffix | Get-NetAdapter<\/p>\n

Get-NetAdapter : No MSFT_NetAdapter objects found with property ‘InterfaceIndex’<\/p>\n

equal to ’44’.  Verify the value of the property and retry.<\/p>\n

At line:1 char:46<\/p>\n

+ Get-DnsClient | ? connectionspecificsuffix | Get-NetAdapter<\/p>\n

+                                              ~~~~~~~~~~~~~~<\/p>\n

    + CategoryInfo          : ObjectNotFound: (44:UInt32) [Get-NetAdapter], CimJobE<\/p>\n

   xception<\/p>\n

    + FullyQualifiedErrorId : CmdletizationQuery_NotFound_InterfaceIndex,Get-NetAda<\/p>\n

   pter<\/p>\n

 <\/p>\n

 <\/p>\n

Name                      InterfaceDescription                    ifIndex Status<\/p>\n

—-                      ——————–                    ——- ——<\/p>\n

vEthernet (WirelessSwi… Hyper-V Virtual Ethernet Adapter #4          31 Up<\/p>\n

Use PowerShell to check the DNS cache<\/h2>\n

Once I see that I have a valid DNS server assigned, I decide to view my DNS cache. I use the Get-DNSCache<\/strong> function as shown here.<\/p>\n

Note<\/strong>   Using the Get-DnsClientCache<\/strong> does not require Admin permissions.<\/p>\n

19:12 C:> Get-DnsClientCache<\/p>\n

Entry                     RecordNameType                Record Status    Section TimeToLive<\/p>\n

—–                     ———-                —— ——    ——- ——<\/p>\n

sxp.microsoft.com         sxp.microsoft.com         CNAME  Success   Answer       4<\/p>\n

ajax.aspnetcdn.com        ajax.aspnetcdn.com        CNAME  Success   Answer     293<\/p>\n

www.facebook.com          www.facebook.com          CNAME  Success   Answer      53\nThere are a couple of things important here. One is the TTL—that is the time-to-live of the record and it lets me know that the spx.microsoft.com record will be present in my DNS cache for 4 seconds. The www.facebook.com<\/a> record will live for 53 seconds.\nA CNAME record<\/a> is a canonical name record, or an alias for a DNS domain. Knowing this information is useful because it lets me know that the domain name I see is not the “actual name” of the server. If using the CNAME to connect to the server does not work, I know where to go to see if the server is even up.\nHere is an example of a CNAME record. I found this by piping a specific entry from the Get-DNSCLientCache<\/strong> to the Format-List<\/strong> cmdlet and, thereby, permitting me to view all of the information. The actual server name exists in the data<\/strong> <\/em>property. I use the following code to obtain the complete information.<\/p>\n

12:35 C:> (Get-DnsClientCache)[0] | fl *<\/p>\n

 TTL                   : 169<\/p>\n

Caption               :<\/p>\n

Description           :<\/p>\n

ElementName           :<\/p>\n

InstanceID            :<\/p>\n

Data                  : prod.us.moneycentral.money.glbdns.microsoft.com<\/p>\n

DataLength            : 8<\/p>\n

Entry                 : moneycentral.msn.com<\/p>\n

Name                  : moneycentral.msn.com<\/p>\n

Section               : 1<\/p>\n

Status                : 0<\/p>\n

TimeToLive            : 169<\/p>\n

Type                  : 5<\/p>\n

PSComputerName        :<\/p>\n

CimClass              : ROOT\/StandardCimv2:MSFT_DNSClientCache<\/p>\n

CimInstanceProperties : {Caption, Description, ElementName, InstanceID…}<\/p>\n

CimSystemProperties   : Microsoft.Management.Infrastructure.CimSystemProperties<\/p>\n

Finding missing records<\/h2>\n

The cool thing about using the Get-DnsClientCache<\/strong> Windows PowerShell cmdlet is that it is PowerShell, and as such, it returns objects. This means an easily parsable output. In the output below, several records are not available—this can obviously cause problems.<\/p>\n

12:51 C:> Get-DnsClientCache<\/p>\n

Entry             RecordNameType       Record Status    Section TimeToLive                                                                <\/p>\n

—–                     ———-                —— ——    ——- ——<\/p>\n

ots.optimize.webtrends… ots.optimize.webtrends… CNAME  Success   Answer     100<\/p>\n

_ldap._tcp.charlottesi…                           SRV    NoRecords<\/p>\n

_ldap._tcp.dc._msdcs.i…                           SRV    NoRecords<\/p>\n

<output truncated>\nBut in a long listing of the DNS client cache, identifying all of the missing records is a bit of a challenge. Therefore, it makes sense to filter the output via the Where-Object<\/strong>. This technique is shown here.<\/p>\n

12:55 C:> Get-DnsClientCache | ? status -eq ‘NoRecords’<\/p>\n

12:55 C:>\nThe problem, unfortunately, is that no records return. The reason is because this is one of those occasions where the actual returned data does not match with the display data—in other words, I am attempting to filter on something that does not exist. To get to the bottom of the problem, I need to see the raw data. I can do that by piping the output to the Format-List<\/strong> cmdlet and viewing all of the properties. This technique is shown here.<\/p>\n

12:55 C:> Get-DnsClientCache | Format-List -Property * -Force<\/p>\n

TTL                   : 0<\/p>\n

Caption               :<\/p>\n

Description           :<\/p>\n

ElementName           :<\/p>\n

InstanceID            :<\/p>\n

Data                  :<\/p>\n

DataLength            : 0<\/p>\n

Entry                 : _ldap._tcp.charlottesite._sites.dc._msdcs.iammred.net<\/p>\n

Name                  :<\/p>\n

Section               : 0<\/p>\n

Status                : 9501<\/p>\n

TimeToLive            : 0<\/p>\n

Type                  : 33<\/p>\n

PSComputerName        :<\/p>\n

CimClass              : ROOT\/StandardCimv2:MSFT_DNSClientCache<\/p>\n

CimInstanceProperties : {Caption, Description, ElementName, InstanceID…}<\/p>\n

CimSystemProperties   : Microsoft.Management.Infrastructure.CimSystemProperties\nI examine the output and see that the status is 9501 <\/em>and not NoRecords. <\/em>Once I change my Where-Object<\/strong> filter, I obtain exactly the output I expected. Here is the modified command and its associated output.<\/p>\n

12:58 C:> Get-DnsClientCache | ? status -eq 9501<\/p>\n

Entry                     RecordNameType                Record Status    Section TimeToLive<\/p>\n

—–                     ———-                —— ——    ——- ——<\/p>\n

_ldap._tcp.charlottesi…                           SRV    NoRecords<\/p>\n

_ldap._tcp.dc._msdcs.i…                           SRV    NoRecords<\/p>\n

_ldap._tcp.5765f6d1-cb…                           SRV    NoRecords<\/p>\n

  12:58 C:>\nJoin me tomorrow when I will talk some more about using Windows PowerShell to troubleshoot DNS issues on the client side.\nI invite you to follow me on Twitter<\/a> and Facebook<\/a>. If you have any questions, send email to me at scripter@microsoft.com<\/a>, or post your questions on the Official Scripting Guys Forum<\/a>. See you tomorrow. Until then, peace.\nEd Wilson, Microsoft Scripting Guy<\/strong><\/p>\n","protected":false},"excerpt":{"rendered":"

Summary: Microsoft Scripting Guy, Ed Wilson, talks about using Windows PowerShell to troubleshoot client DNS. Microsoft Scripting Guy, Ed Wilson, is here. It seems that when I travel invariably at some point on the trip I end up in a hotel that has DNS issues. In the past, that meant opening up the CMD prompt […]<\/p>\n","protected":false},"author":596,"featured_media":87096,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[1],"tags":[396,37,3,45],"class_list":["post-4359","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-scripting","tag-dns","tag-networking","tag-scripting-guy","tag-windows-powershell"],"acf":[],"blog_post_summary":"

Summary: Microsoft Scripting Guy, Ed Wilson, talks about using Windows PowerShell to troubleshoot client DNS. Microsoft Scripting Guy, Ed Wilson, is here. It seems that when I travel invariably at some point on the trip I end up in a hotel that has DNS issues. In the past, that meant opening up the CMD prompt […]<\/p>\n","_links":{"self":[{"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/posts\/4359","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/users\/596"}],"replies":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/comments?post=4359"}],"version-history":[{"count":0,"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/posts\/4359\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/media\/87096"}],"wp:attachment":[{"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/media?parent=4359"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/categories?post=4359"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/tags?post=4359"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}