{"id":11051,"date":"2012-02-24T00:01:00","date_gmt":"2012-02-24T00:01:00","guid":{"rendered":"https:\/\/blogs.technet.microsoft.com\/heyscriptingguy\/2012\/02\/24\/use-powershell-to-test-connectivity-on-remote-servers\/"},"modified":"2012-02-24T00:01:00","modified_gmt":"2012-02-24T00:01:00","slug":"use-powershell-to-test-connectivity-on-remote-servers","status":"publish","type":"post","link":"https:\/\/devblogs.microsoft.com\/scripting\/use-powershell-to-test-connectivity-on-remote-servers\/","title":{"rendered":"Use PowerShell to Test Connectivity on Remote Servers"},"content":{"rendered":"

Summary<\/b>: Microsoft Scripting Guy talks about using Windows PowerShell to test connectivity after a network configuration change.<\/p>\n

Microsoft Scripting Guy, Ed Wilson, is here. It seems that there are always good news\/bad news <\/i>types of scenarios. After months of trying to obtain faster Internet connectivity at the house, I finally found a source that doubled the upload and download speeds for the Scripting Wife and I, at literally half the price we had been paying. Talk about a deal. Talk about not just good news, <\/i>but GREAT NEWS. <\/i>Now for the bad news <\/i>part of the equation…<\/p>\n

The router they showed up with at the house—part of the free installation—would not accept a static IP address on the Ethernet side of the equation that was compatible with my current network configuration—and I have a relatively complex configuration that involves multiple subnets.<\/p>\n

Writing a quick script to ensure connectivity<\/h2>\n

When I ran into problems, I decided to write a really quick script to ping the most critical servers on my network to ensure connectivity. I wanted to ensure that DNS resolution worked, so I did the ping by name instead of by IP address. I manually created an array of computer names that I stored in a variable called $servers<\/b>. To walk through the array of servers, I used the ForEach<\/b> <\/i>statement. The $s<\/b> variable represents the actual computer name inside the loop. This is shown here.<\/p>\n

$servers = “dc1″,”dc3″,”sql1″,”wds1″,”ex1”<\/p>\n

Foreach($s in $servers)<\/p>\n

{<\/p>\n

To ping the computers, I use the Test-Connection <\/b>cmdlet. In the definition of the Test-Connection <\/b>command, I determine the buffer size, the number of pings to submit, and whether it returns detailed ping status information or a simple Boolean value. I specify the ea <\/i>parameter (ea <\/i>is an alias for the ErrorAction <\/i>parameter) value of 0. The value of 0 tells the cmdlet to not display error information (an error displays when a ping is unsuccessful).<\/p>\n

Note   <\/b>For more information about using the Test-Connection<\/b>, cmdlet refer to Query AD for Computers and Use Ping to Determine Status<\/a>.<\/p>\n

Because the cmdlet returns a Boolean value, I am able to simplify the code a bit. I therefore state that if the command does not return a True value, I want to perform additional actions. This portion of the script is shown here.<\/p>\n

if(!(Test-Connection -Cn $s -BufferSize 16 -Count 1 -ea 0 -quiet))<\/p>\n

  {<\/p>\n

Because I am hiding errors that are returned from the Test-Connection <\/b>cmdlet, I decided to display my own status information. I print out a message that lets me know a problem occurs with reaching the computer. I then decide to run three commands. The first flushes the DNS cache, the second updates the DNS registration, and the third performs an NSLookup<\/b> on the server. Finally, I ping the computer again. This portion of the script is shown here.<\/p>\n

“Problem connecting to $s”<\/p>\n

   “Flushing DNS”<\/p>\n

   ipconfig \/flushdns | out-null<\/p>\n

   “Registering DNS”<\/p>\n

   ipconfig \/registerdns | out-null<\/p>\n

   “doing a NSLookup for $s”<\/p>\n

   nslookup $s<\/p>\n

   “Re-pinging $s”<\/p>\n

     if(!(Test-Connection -Cn $s -BufferSize 16 -Count 1 -ea 0 -quiet))<\/p>\n

      {“Problem still exists in connecting to $s”}<\/p>\n

       ELSE {“Resolved problem connecting to $s”} #end if<\/p>\n

   } # end if<\/p>\n

} # end foreach<\/p>\n

When I ran the PingTest.ps1 script on my computer, the following output appeared in the Windows PowerShell ISE.<\/p>\n

\"Image<\/a><\/p>\n

The complete PingTest.ps1 script is shown here.<\/p>\n

PingTest.PS1<\/strong><\/p>\n

$servers = “dc1″,”dc3″,”sql1″,”wds1″,”ex1”<\/p>\n

Foreach($s in $servers)<\/p>\n

{<\/p>\n

  if(!(Test-Connection -Cn $s -BufferSize 16 -Count 1 -ea 0 -quiet))<\/p>\n

  {<\/p>\n

   “Problem connecting to $s”<\/p>\n

   “Flushing DNS”<\/p>\n

   ipconfig \/flushdns | out-null<\/p>\n

   “Registering DNS”<\/p>\n

   ipconfig \/registerdns | out-null<\/p>\n

  “doing a NSLookup for $s”<\/p>\n

   nslookup $s<\/p>\n

   “Re-pinging $s”<\/p>\n

     if(!(Test-Connection -Cn $s -BufferSize 16 -Count 1 -ea 0 -quiet))<\/p>\n

      {“Problem still exists in connecting to $s”}<\/p>\n

       ELSE {“Resolved problem connecting to $s”} #end if<\/p>\n

   } # end if<\/p>\n

} # end foreach<\/p>\n

This script took me less than five minutes to write, and it saved me much more time than that if I had to do a lot of manual troubleshooting. If I needed the output to a text file, I would have called the script from the Windows PowerShell console and redirected the output to a text file. I did not need to do that, but it would have been simple.<\/p>\n

Note<\/b>   For more information about writing to text files, see The Scripting Wife Learns to Work with Text Files.<\/i><\/a><\/p>\n

If I needed to run the script from each of the critical servers (so they could check for connectivity to each other), I would have copied the script to a network share, and then used Windows PowerShell remoting to run the script on each of the servers. I would also have redirected the output to a text file, but in this example, I would have used a text file on the same network share as the script.<\/p>\n

Note   <\/b>For more information about Windows PowerShell remoting, see these Hey, Scripting Guy! blogs<\/a>.<\/p>\n

I invite you back tomorrow for the Weekend Scripter, when I will talk about copying Windows PowerShell Scripts to a network share.<\/p>\n

I 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.<\/p>\n

Ed Wilson, Microsoft Scripting Guy<\/b><\/p>\n","protected":false},"excerpt":{"rendered":"

Summary: Microsoft Scripting Guy talks about using Windows PowerShell to test connectivity after a network configuration change. Microsoft Scripting Guy, Ed Wilson, is here. It seems that there are always good news\/bad news types of scenarios. After months of trying to obtain faster Internet connectivity at the house, I finally found a source that doubled […]<\/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":[36,218,188,37,3,4,45,77],"class_list":["post-11051","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-scripting","tag-client-side-management","tag-dhcp-server","tag-dns-server","tag-networking","tag-scripting-guy","tag-scripting-techniques","tag-windows-powershell","tag-writing"],"acf":[],"blog_post_summary":"

Summary: Microsoft Scripting Guy talks about using Windows PowerShell to test connectivity after a network configuration change. Microsoft Scripting Guy, Ed Wilson, is here. It seems that there are always good news\/bad news types of scenarios. After months of trying to obtain faster Internet connectivity at the house, I finally found a source that doubled […]<\/p>\n","_links":{"self":[{"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/posts\/11051","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=11051"}],"version-history":[{"count":0,"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/posts\/11051\/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=11051"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/categories?post=11051"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/tags?post=11051"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}