|DNS – Blog|
|Time to Read|
|Who should read this blog.?|
|If you want to learn how to add Reverse Lookup Zone in Windows Server|
A DNS Reverse Lookup Zone is a DNS zone that is used to map IP addresses to domain names. It is essentially the opposite of a regular DNS zone, which maps domain names to IP addresses.
When a DNS Reverse Lookup Zone is set up, a DNS server can be queried with an IP address, and the server will respond with the corresponding domain name. This can be useful for troubleshooting network issues or for security purposes, as it allows you to identify the domain name associated with a particular IP address.
For example, if someone performs a reverse DNS lookup on the IP address 192.168.1.1 and a PTR record exists in the reverse lookup zone that maps this IP address to the hostname “thecloudblogger.com”, then the reverse DNS lookup will return “thecloudblogger.com” as the result.
Learn more about DNS in my blog What is DNS?
It all starts with Server Manager
As we log in to the Windows Server, the first screen we will see of the Server Manager
To configure the Reverse Lookup Zone we should have DNS Service already installed and configured. In my previous blog, I have already explained how to install and configure DNS Server Install and Configure DNS Server on Windows Server. So we are ready.
Browse DNS to configure
This is the screen you will see
Right-click on Reverse Lookup Zone and Select ‘New Zone..’
Click on the ‘Next‘ Button
Choose Zone Types
There are different Zone types and the good news is that I have covered them in detail
Refer to my blog which covers in detail about Primary DNS Server and Secondary DNS Servers.
Kindly note zone is formed on the servers. So Primary servers will hold the primary zone while the secondary servers will hold the secondary zone. So in a way, they represent the same thing.
Back to our configuration –
Select ‘Primary zone’ as the zone Type and hit ‘Next‘
Select the Reverse Lookup zone
Based on your network address schema you may select IPv4 or IPv6 Reverse Lookup zone
In our setup, we will select IPv4 as our Network is using IPv4 Schema.
Enter Network Id
When configuring a reverse lookup zone, the network ID refers to the first three octets (or 24 bits) of an IP address that identify the network to which the IP address belongs. In a reverse lookup zone, the network ID is used to create a PTR (pointer) record that maps an IP address to a hostname.
For example, if the IP address is 192.168.1.1 and the subnet mask is 255.255.255.0, then the network ID is 192.168.1.0. When configuring the reverse lookup zone for this network, a PTR record would be created for 188.8.131.52.in-addr.arpa. where “192.168.1” is the reversed network ID.
Enter Zone File Name
A Zone file is a text file that contains the DNS resource records for a particular DNS zone and is used by the DNS server software to resolve domain names to IP addresses. These record types are SOA, NS, A, AAAA, CNAME, MX, and TXT.
Learn more about record types on my blog – Types of DNS Records
This file can be used to move the existing records to a New Server the process is called Zone Transfer.
Back to our configuration –
We are creating a New Reverse Zone file whose name is automatically filled with our Network id(in reverse order) appended with ‘.in-addr.arpa.dns’ and hit ‘Next‘
Setting up Dynamic Update
Updating a zone in a large and ever-changing network could be a tedious task, hence instead of manually updating the zone record, the Dynamic update option can be enabled. In a dynamic update scenario, a DNS client or a DNS server sends an update request to the DNS server responsible for the zone.
The update request contains the new or modified DNS resource record that needs to be added or updated in the zone. The DNS server verifies the update request and applies the changes to the zone. This saves manual interventions and increases the consistency of DNS records.
However, dynamic updates also pose security risks since anyone who has access to the network can potentially make changes to the DNS zone. To mitigate these risks, it is important to implement appropriate security measures such as secure zone transfers, access control lists, and transaction signatures (TSIG) to authenticate update requests.
Back to our configuration –
We don’t want Dynamic Updates – hence select ‘Do not allow dynamic updates
and hit ‘Next’
We are all set
Our Reverse zone ‘1.168.192.in-addr.arpa‘ is all set the moment you hit the ‘Finish’ button.
The zone is served hot
Our First zone is configured and ready.
Adding the first record in our new zone
As we can see there are 2 records already existing the SOA and Name-Server records. These records are automatically added by the DNS service itself after a zone is created.
To know more about SOA and NS records refer to my blog Public DNS Infrastructure and DNS Server types
Back to our configuration – Right-click on the newly created zone and add a new PTR record. Refer to my blog Types of DNS Records to know more about record types.
Add record details
Add the Host IP Address and Host-name as specified below and click on the ‘ok‘ button.
A new record is added
As highlighted with an arrow one new PTR record can be seen.
Go to the CMD prompt of the server or your client machine if it is using our configured DNS server.
type nslookup 192.168.1.1 and it resolves correctly to host-name thecloudblogger.com.
C:\Users\Admin>nslookup 192.168.1.1 Server: UnKnown Address: 10.1.0.6 Name: thecloudblogger.com Address: 192.168.1.1
In this blog, Forward Reverse Zone was configured with a PTR record and tested successfully.
Read more: How to add DNS Reverse Lookup Zone in Windows Server