Tag Archive: DNS


DNS to change a dynamic record to a static record

http://social.technet.microsoft.com/wiki/contents/articles/21726.how-to-convert-a-dynamic-resource-record-to-a-static-one-without-re-creating-it-in-dns.aspx

 

DNS PowerShell – import-module DNSServer

example: http://www.rivnet.ro/category/active-directory/dns

 

DNS Powershell – DnsShell

 Summary: Learn how to use a free Windows PowerShell module to ease administration of Windows DNS: DnsShell (http://dnsshell.codeplex.com/)

What is DnsShell?

The majority of the cmdlets in DnsShell are wrappers around the WMI interface. The WMI interface tends to be fairly difficult to work with, or at least more difficult than it needs to be. For the most part this is due to the infamous Generic Error it returns whenever something goes wrong.

In addition to the WMI wrappers, DnsShell contains an interface for working with DNS via LDAP with decoders for the dnsProperty and dnsRecord attributes.

The final cmdlet, Get-Dns, is a DNS resolver, designed to exceed the capabilities of nslookup and to be comparable with Dig.

This post aims to explore some of the capabilities for DnsShell, based on the tasks I use it for on a regular basis.

Basic tasks

Listing zones

Get-DnsZone can be used to return information about zones configured on a server. This cmdlet uses WMI to grab details of the zone. The parameters used with this cmdlet are used to
build a WQL filter.

# All zones

Get-DnsZone

# Primary zones

Get-DnsZone -ZoneType Primary | Format-List

Zone information can be returned from Active Directory using Get-ADDnsZone. By default, Get-ADDnsZone targets the DomainDnsZones application partition.

The information returned by this cmdlet differs slightly from Get-DnsRecord, only showing detail stored in the dnsProperty attribute.

# Returning all zones in DomainDnsZoness (for the current domain)

Get-ADDnsZone

# Returning all zones from all partitions

Get-ADDnsPartition | Get-ADDnsZone

Listing records

The following examples demonstrate how Get-DnsRecord can be used to pick up records configured on a server.

# Listing all records on the current server

Get-DnsRecord

# List A records in domain.example only

Get-DnsRecord -RecordType A -Zone domain.example

# List all static records on the server

Get-DnsRecord -Filter “TimeStamp=0”

# Name is a regular expression and can be used for simple or complex filters

Get-DnsRecord -Name ‘_tcp’ -RecordType SRV

Get-ADDnsRecord may also be to retrieve record information. By its nature Get-ADDnsRecord is limited to querying records stored in Active Directory-integrated zones.

# All records in the DomainDnsZones partition

Get-ADDnsRecord

# All Service (SRV) records in all partitions

Get-ADDnsPartition | Get-ADDnsRecord | Where-Object { $_.RecordType -eq “SRV” }

# Name supports wildcards (used to build an LDAP filter)

Get-ADDnsRecord -Name “_gc*”

# List all records in a specific zone

Get-ADDnsZone domain.example | Get-ADDnsRecord

Unlike Get-DnsRecord, which offers a parameter to filter on RecordType, Get-ADDnsRecord is reliant on Where-Object. This is used because
is no way to construct an LDAP Filter to limit a search to specific record types as the record type is encoded as part of the dnsRecord
attribute. Wildcards or partial matches are not permissible for DnsRecord as it is a Binary Large Object (BLOB).

The RecordType field used above is defined in an Enumeration. The possible values can be seen with:

[Enum]::GetNames([DnsShell.RecordType])

Using the following filter for Where-Object returns the same results, it is equivalent to the filter above:

# Get all records from AD (DomainDnsZones). Filter to Service Records

Get-ADDnsRecord | Where-Object { $_.RecordType -eq [DnsShell.RecordType]::SRV }

Returning server configuration

Returning a DNS servers configuration is a simple task. The Get-DnsServer cmdlets returns each of the configuration options available to MS DNS server.

# Ask for DNS Server settings from $ServerName

Get-DnsServer $ServerName

Creating zones

New-DnsZone uses the CreateZone method from WMI, checking for a few potential errors along the way.

# A new standard Primary forward lookup zone. Returns an object representing the new zone

New-DnsZone domain.example -ZoneType Primary -PassThru

Creating records

New-DnsRecord is one of the most complex cmdlets in the module. It provides an abstract interface to the CreateInstanceFromPropertyData method on each of the record classes.
Many of the parameters accept pipeline input to further simplify usage.

# A new Host (A) record

New-DnsRecord -Name mail -RecordType A -Zone domain.example -IPAddress 1.2.3.4

# A new Mail Exchanger (MX) record

New-DnsRecord -RecordType MX -Zone domain.example ‘

-TargetName mail.domain.example -Preference 10

Advanced tasks

Automating secondary zone setup

On occasion it is nice to be able to create secondary zones for every Primary zone on another server.

# Alternate credentials for this operation

$Credential = Get-Credential

# The Primary server name (used to access WMI) and the  IP address $SecondaryServer will use to access the Primary

$PrimaryServer = “ThePrimaryServer”; $PrimaryIP = “1.2.3.4”

# A secondary server name (used to access WMI)

$SecondaryServer = “TheSecondaryServer”

# Get all Primary Forward Lookup Zones from $PrimaryServer and create a corresponding Secondary zone on $SecondaryServer

Get-DnsZone -ZoneType Primary -Filter “Reverse=$False” ‘

-Server $PrimaryServer -Credential $Credential |

New-DnsZone -ZoneType Secondary -MasterServer $PrimaryIP  -Server $SecondaryServer -PassThru

A ForEach (either ForEach or ForEach-Object) loop is not necessary to accomplish this, however it may be added if greater control over the process is required.

Get-DnsZone -ZoneType Primary -Filter “Reverse=$False” -Server $PrimaryServer -Credential $Credential |

ForEach-Object
{
# See if the zone exists on $SecondaryServer first
If (!(Get-DnsZone $_.Name -Server $SecondaryServer)) {
# If it does not (!), create the zone
New-DnsZone
$_.Name -ZoneType Secondary -MasterServer $PrimaryIP -Server $SecondaryServer -PassThru
}
}

Strictly speaking, the ForEach-Object loop is still not an absolute requirement in this example. Where-Object can be used to filter down to zones that only do not exist on the Primary.

Adding A and PTR records from a CSV file

One common task is the addition of A and corresponding PTR records. To demonstrate this script a simple CSV file can be used.

Name,IPAddress
www,192.168.1.1
ftp,192.168.1.2
mail,192.168.1.3

The tricky part is adding the PTR records without having to manually define the Reverse Lookup Zone name. One possible way to deal with this is to send a
DNS query; an approach is similar to that used by dynamic update, a query which attempts to find a server willing to accept an update.

In the example below, Get-Dns is used to execute a query for the PTR record. The expected response is NXDOMAIN (doesn’t exist), but that response will contain an Authority section including the server and zone name.
That zone name can be used to make the new record.

$ServerName = “TheServer”
$ForwardLookupZone = “domain.example”
Import-Csv Records.csv | ForEach-Object {
# Create the record in the Forward Lookup Zone
New-DnsRecord -Name $_.Name -IPAddress $_.IPAddress -Zone $ForwardLookupZone -Type A -Server $ServerName
# Find the name of the reverse lookup zone
$ReverseLookupZone = (Get-Dns $_.IPAddress -RecordType PTR -Server $ServerName).Authority[0].Name
# Create the record in the Reverse Lookup Zone
New-DnsRecord -Name $_.IPAddress -Hostname “$($_.Name).$ForwardLookupZone” -Zone $ReverseLookupZone -Type PTR -Server $ServerName
}

Debugging name resolution with Get-Dns

Debugging name resolution under Microsoft Windows is typically limited to either nslookup or the client resolver (normally via ping). Get-Dns is more comprehensive, capable of both simple and complex queries.

Note: The examples below make extensive use of domain.example.
This should be replaced with a valid domain name, many of the examples will return nothing if taken literally.

The following command performs a Zone Transfer, used when a Secondary server picks up a copy of the zone from a Primary Server. This operation should not be confused with replication of zone data when Active Directory-integrated zones are in use. This command requires access to TCP Port 53 on the server holding the zone (most DNS traffic uses UDP Port 53).

# Equivalent of nslookup using ls -d domain.example
Get-Dns domain.example -Transfer
# Or
Get-Dns domain.example axfr

Tracing a request from root using an iterative query; used to verify the delegation chain, to test that DNS requests are directed to the correct servers. The initial servers (Root Hints) are taken from the locally configured DNS service.

# Performs a search for the record from the Root DNS servers (display all hops)
# Equivalent of dig domain.example +trace
Get-Dns domain.example -Iterative

NsSearch can be used to check that all DNS servers for a domain name reply with the same (or intended) answer. If the answers are different clients may experience problems accessing
a resource.

# Returns the A record for domain.example from all authoritative name servers
# Equivalent for dig domain.example a +nssearch
Get-Dns domain.example -RecordType A -NsSearch

Get-Dns returns all of the fields from a DNS packet by default; this makes the return value a complex nested object. Specific parts of the return value can be selected as demonstrated in the following examples.

# Expanding the answer
Get-Dns http://www.domain.example a -NsSearch | Select-Object -ExpandProperty Answer
# If only one response is returned
(Get-Dns http://www.domain.example a).Answer
# Just the Header
Get-Dns domain.example | Select-Object -ExpandProperty Header
# Question, Answer, Authority and Additional are always arrays. An element number must be used when accessing fields even if only one item exists.
(Get-Dns http://www.domain.example a).Question[0].Name
(Get-Dns http://www.domain.example a).Question.Count
(Get-Dns http://www.domain.example a).Question.GetType()
# Answer and Flags
Get-Dns domain.example | Select-Object Answer, @{n=’Flags’;e={ $_.Header.Flags
}}

# The server, status code (RCode) and time taken (in milliseconds) for an Iterative query
Get-Dns domain.exmaple -Iterative | Select-Object Server, TimeTaken,
@{n=’RCode’;e={ $_.Header.RCode }}

How to retrieve the computer name based on the IP?

this mechanism is called “reverse lookup”. In general it works if your DNS server contain “reverse zones” and reverse records.

In that case, the following commands works fine:

ping -a <IP>

nslookup -a <IP>

But if your internal DNS Server, does not contain reverse zone. You must request records from your DNS server directly.

To achieve that, you can use nslookup or powershell to get an answer from a DNS server:

a) using nslookup

nslookup

server <enter remote DNS>

<type the IP>

 

b) using Powershell

#
# Get DNS records (computer FQDN) based on list of IPs (input)
#
# Created    :     10/01/2012
# Updated    :    21/03/2013
#
# Authors    : jdalbera – gbs-its-wid-nce
# Comments    : This script query the current DNS to retrieve list of FQDN corresponding
# to list of IPs (reverse records)
# It writes the results to a text file
#
cls
Write-Host “”
Write-Host “——————————————————-”
Write-Host ” Get DNS records from list of IPs ”
Write-Host “——————————————————-”
Write-Host “”

## VARIABLES
$date = Get-Date -Format ddMMyyyy
$log = “.\logs\Get-DNSrecordFromIPs-$date.txt”
#$listofIPs = Get-Content .\IPList.txt
$listofIPs = “10.64.23.23”,”10.65.10.12″,”10.66.10.11″
#Lets create a blank array for the resolved names
$ResultList = @()

## MAIN
Write-host “”
Write-host “————————————————————————————————”
Write-host “”
$startscript = Get-Date

# Lets resolve each of these addresses
foreach ($ip in $listofIPs)
{
$result = $null
$currentEAP = $ErrorActionPreference
$ErrorActionPreference = “silentlycontinue”

#Use the DNS Static .Net class for the reverse lookup
# details on this method found here: http://msdn.microsoft.com/en-us/library/ms143997.aspx
$result = [System.Net.Dns]::gethostentry($ip)
$ErrorActionPreference = $currentEAP
If ($Result) {
$Resultlist += [string]$Result.HostName
}
Else {
$Resultlist += “$IP – No HostNameFound”
}
}
# To output the results to a text file
$resultlist | Out-File $log

Write-host “——————-”
Write-host “– End of Script –”
Write-host “——————-”
Write-host “”
$stopscript = Get-Date
Write-host “Has started at” $startscript -BackgroundColor Gray -ForegroundColor Black
Write-host “Had finished at” $stopscript -BackgroundColor Gray -ForegroundColor Black
Write-host “TIME SPENT:” (New-TimeSpan -Start $startscript -End $stopscript).hours “Hours” (New-TimeSpan -Start $startscript -End $stopscript).minutes “Minutes” (New-TimeSpan -Start $startscript -End $stopscript).seconds “Seconds” -BackgroundColor Green -ForegroundColor Black
Write-host “”
Write-host “”

IP Address Management (IPAM) in Windows Server 2012 is a framework for discovering, monitoring, managing and auditing IP address space on a corporate network. IPAM provides the following features:

  • Automatic IP address infrastructure discovery
  • Highly customizable IP address space display, reporting, and management
  • Configuration change auditing for DHCP and IPAM services
  • Monitoring and management of DHCP and DNS services
  • IP address lease tracking

Web resources:

http://technet.microsoft.com/en-us/library/jj878339.aspx

http://blogs.technet.com/b/canitpro/archive/2013/08/15/step-by-step-setup-windows-server-2012-ipam-in-your-environment.aspx

 

 

Collection of Web resources about dig usage:

http://www.danesparza.net/2011/05/using-the-dig-dns-tool-on-windows-7/

http://anouar.adlani.com/2011/12/useful-dig-command-to-troubleshot-your-domains.html

https://library.linode.com/linux-tools/common-commands/dig

Download dig (part of Bind):

http://www.isc.org/downloads/

Some commands:

What is the website’s IP address ?

dig +short amazon.com

How to identify the name servers associated with a domain ?

dig NS +short anouar.im

What does the delegation path to my zone look like ?

dig google.com +trace

Which Mail Server is responsible for a domain ?

dig MX adlani.com

Which value is in cache in a given resolver ?

dig google.com @8.8.8.8

Which domain name is this IP associated with ?

dig +short -x 8.8.8.8

Which are the name servers of a TLD ?

dig +short NS nl.

When will the cache of an answer expire ?

dig google.com +noall +answer

Is the zone synchronized to all my NS ?

dig google.com +nssearch

Is a zone existing on this name server ?

dig SOA google.nl @ns1.nic.nl.

Using Dig to Retrieve Different Record Types?

dig srv _jabber._tcp.example.com
 

 

 

 

 

what’s new in DNS on Windows 2012 server ? http://technet.microsoft.com/en-us/library/hh831667.aspx

understanding DNS ? http://technet.microsoft.com/library/cc732997(WS.10).aspx

How works DNS queries and processes/interactions/dynamic updates… : http://technet.microsoft.com/en-us/library/dd197552(v=ws.10).aspx

How to access DNS application partition (AD-integrated-DNS zone) with adsiedit.msc:

from adsiedit,  Connect to the partition:  Dc=domainDnszones,dc=mydom,dc=domain,dc=net

Then expand to go to mydom.domain.net

You can find all the DNS records,

Select the CN=MYCOMPUTER1 for instance, right-click properties, edit attributes

Check the attribute value “whenChanged” you have the real time when the DNS record has been modified (real timestamp !)