PS C:\\> 111 -match \"^\\d{1,3}\"\nTrue\n<\/pre>\nBut what happens if someone adds in four numbers: Will we get a false reading?<\/p>\n
PS C:\\> 1111 -match \"^\\d{1,3}\"\nTrue\n<\/pre>\nAs a matter of fact, we do not because the first three positions have numbers, and we said nothing about the end. After we add in our period, we now get a false match. When we test it with three numbers followed by a period and an additional number, we once again get a match.<\/p>\n
PS C:\\> \"1111\" -match \"^\\d{1,3}\\.\"\nFalse\nPS C:\\> \"111.1\" -match \"^\\d{1,3}\\.\"\nTrue\n<\/pre>\nWe continue in this manner, until we come to the end of the pattern, which we specify as ending in 1 to 3 numbers. The $<\/b> sign matches the end. Our completed regular expression pattern match is seen here: <\/p>\nIf($ipHost -match \"^\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}$\")\n<\/pre>\nIf the value of $ipHost<\/b> makes it past our regular expression pattern match, we call the static GetHostEntry<\/b> method, and return only the HostName<\/b> property from the returned object. To use the System.Net.Dns<\/b> .NET Framework class, we put the name of the class in square brackets, use two colons (because this is a static method), call the method name, and supply it the value of the $iphost<\/b> variable:<\/p>\n{\n [System.Net.Dns]::GetHostEntry($iphost).HostName\n }\n<\/pre>\nIf the value of $ipHost<\/b> makes it past our regular expression pattern match, we call the static GetHostEntry<\/b> method, and return only the HostName<\/b> property from the returned object. To use the System.Net.Dns<\/b> .NET Framework class, we put the name of the class in square brackets, use two colons (because this is a static method), call the method name, and supply it the value of the $iphost<\/b> variable:<\/p>\n{ [System.Net.Dns]::GetHostEntry($iphost).HostName }<\/pre>\nIf the $ipHost<\/b> value does not match the IP address regular expression pattern, we see if it matches another pattern. This pattern looks for any character .*<\/b> followed by a single period and then any other number of characters. This will match domain names with dashes, numbers, and letters in them. But it must have at least one period in the name. If a host name was passed in the $iphost<\/b> variable, we obtain the AddressList<\/b> property, and then retrieve the IPAddressToString<\/b> property. Because the AddressList<\/b> property is an array, we need to index into the array to retrieve a single value prior to converting it to a string. On many systems, this approach will be fine, but on Windows Vista and later the first IP address will be IPv6 and the second one IPv4. This is seen in this image: <\/p>\n
![\"Image](\"http:\/\/img.microsoft.com\/library\/media\/1033\/technet\/images\/scriptcenter\/qanda\/hsg\/2009\/february\/hey0226\/hsg-02-26-9-01.jpg\")
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After we are done looking at the IP address that was submitted, we examine the host name to ensure it has a period in the name, has characters separated by a period, and has some more characters. This ensures that the dotted notation familiar to virtually all users of the internet is contained in the $IPHost<\/b> variable. The command will kick out an attempt to resolve a simple netbios name:<\/p>\nElseIf( $ipHost -match \"^.*\\.\\.*\")\n {\n [System.Net.Dns]::GetHostEntry($iphost).AddressList[0].IPAddressToString\n }\n<\/pre>\nWhen the value of $iphost<\/b> does not match our IP address pattern or our host name pattern, we throw an error and state that the user needs to supply the appropriate value to the function: <\/p>\nELSE { Throw \"Specify either an IP V4 address or a hostname\" }\n} #end Get-DnsEntry\n<\/pre>\nThe entry point to the script calls the Get-DnsEntry<\/b> function and passes a hostname value to it. You can replace this line with one that takes command-line arguments or make whatever types of modifications to the function you wish. The entry point is seen here. <\/p>\nGet-DnsEntry \"Vista.NwTraders.Com\"<\/pre>\nWell, BP, we have come to the end of the Get-DnsEntry.ps1<\/b> script. We finished a little early, so perhaps we have time to go and watch Spice World.(Okay, maybe not. I\u2019ll probably wait another decade to watch it again.) This also concludes our DNS Week articles. See you tomorrow for Quick-Hits Friday. See you tomorrow. <\/p>\n
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Ed Wilson and Craig Liebendorfer, Scripting Guys<\/b><\/p>\n","protected":false},"excerpt":{"rendered":"
Hey, Scripting Guy! I know I can use the DNS WMI provider and query a DNS server. But what if I am not using a Microsoft DNS server? Or what if I do not have admin rights on the DNS server? What happens then? I really do not want to resort to parsing the output […]<\/p>\n","protected":false},"author":595,"featured_media":87096,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[1],"tags":[188,37,3,45],"class_list":["post-54303","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-scripting","tag-dns-server","tag-networking","tag-scripting-guy","tag-windows-powershell"],"acf":[],"blog_post_summary":"
Hey, Scripting Guy! I know I can use the DNS WMI provider and query a DNS server. But what if I am not using a Microsoft DNS server? Or what if I do not have admin rights on the DNS server? What happens then? I really do not want to resort to parsing the output […]<\/p>\n","_links":{"self":[{"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/posts\/54303","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\/595"}],"replies":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/comments?post=54303"}],"version-history":[{"count":0,"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/posts\/54303\/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=54303"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/categories?post=54303"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/tags?post=54303"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
![\"Hey,](\"https:\/\/devblogs.microsoft.com\/wp-content\/uploads\/sites\/29\/2019\/02\/q-for-powertip.jpg\" "\\"Hey,")
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![\"Hey,](\"https:\/\/devblogs.microsoft.com\/wp-content\/uploads\/sites\/29\/2019\/02\/a-for-powertip.jpg\" "\\"Hey,")
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