DNS Health Check

http://portal.ultradns.com/premium/ultratools.jsp
 

DNS Health Check

http://portal.ultradns.com/premium/ultratools.jsp
 

Dig Web Interface

1.    Browse to http://www.digwebinterface.com/

2.    Enter the list of hosts you wish to test under Hostnames or IP addresses:

3.    Select Resolver under Name Servers:

4.    Check Trace under Options

5.    Click Dig

First section of results are root servers.
Next section are authoritative name servers for the TLD
Next section (your domain) are the NS records from the domain registry.
Next section (your domain) are the NS records provided an authoritative NS

Duplicate IP address registrations in DNS

Duplicate IP address registrations in DNS


https://blogs.technet.microsoft.com/askpfe/2011/06/03/how-dns-scavenging-and-the-dhcp-lease-duration-relate/


Very useful discussion of this issue and methods to address it.


Also a script to identify duplicate IP addresses in DNS:

#
#Import the Active Directory Module
import-module activedirectory

#Define an empty array to store computers with duplicate IP address registrations in DNS
$duplicate_comp = @()

#Get all computers in the current Active Directory domain along with the IPv4 address
#The IPv4 address is not a property on the computer account so a DNS lookup is performed
#The list of computers is sorted based on IPv4 address and assigned to the variable $comp
$comp = get-adcomputer -filter * -properties ipv4address | sort-object -property ipv4address

#For each computer object returned, assign just a sorted list of all 
#of the IPv4 addresses for each computer to $sorted_ipv4
$sorted_ipv4 = $comp | foreach {$_.ipv4address} | sort-object

#For each computer object returned, assign just a sorted, unique list 
#of all of the IPv4 addresses for each computer to $unique_ipv4
$unique_ipv4 = $comp | foreach {$_.ipv4address} | sort-object | get-unique

#compare $unique_ipv4 to $sorted_ipv4 and assign just the additional 
#IPv4 addresses in $sorted_ipv4 to $duplicate_ipv4
$duplicate_ipv4 = Compare-object -referenceobject $unique_ipv4 -differenceobject $sorted_ipv4 | foreach {$_.inputobject}

#For each instance in $duplicate_ipv4 and for each instance 
#in $comp, compare $duplicate_ipv4 to $comp If they are equal, assign
#the computer object to array $duplicate_comp
foreach ($duplicate_inst in $duplicate_ipv4)
{
    foreach ($comp_inst in $comp)
    {
        if (!($duplicate_inst.compareto($comp_inst.ipv4address)))
        {
            $duplicate_comp = $duplicate_comp + $comp_inst
        }
    }
}

#Pipe all of the duplicate computers to a formatted table
$duplicate_comp | ft name,ipv4address -a

Check DNS Propagation

Great online utility to check propagation of DNS changes.https://www.whatsmydns.net