How to set up reverse DNS for a private IP address on an Ubuntu server. Reverse DNS lookup is used to map an IP address to a domain name, but this is typically done for public IP addresses, not private ones.
Configuring Reverse DNS with BIND on Ubuntu Server
Private IP addresses like 10.0.0.1 are commonly used within internal networks (e.g., home or office networks) and are not routable on the public internet. Reverse DNS for such addresses would be managed within the local network and not by public DNS servers.
If you need to set up reverse DNS for a private IP address within your local network, you would typically configure this on your internal DNS server (e.g., using BIND, Microsoft DNS, etc.).
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To set up reverse DNS for a private IP address (e.g., 10.0.0.2) on an Ubuntu server, you would typically use BIND (Berkeley Internet Name Domain). Below are the steps to configure BIND for reverse DNS:
Add the following zone definitions to configure both forward and reverse lookup zones. Replace example.com with your domain name.
bashCopy codezone "example.com" { type master; file "/etc/bind/db.example.com"; };
zone "0.0.10.in-addr.arpa" { type master; file "/etc/bind/db.10.0.0"; };
Create the Forward Lookup Zone File
Create the forward lookup zone file.
bashCopy codesudo nano /etc/bind/db.example.com
Add the following content to the file. Replace example.com and ns1.example.com with your actual domain and nameserver information.
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pythonCopy code$TTL 604800 @ IN SOA ns1.example.com. admin.example.com. ( 2024072101 ; Serial 604800 ; Refresh 86400 ; Retry 2419200 ; Expire 604800 ) ; Negative Cache TTL ; @ IN NS ns1.example.com. ns1 IN A 10.0.0.1 server1 IN A 10.0.0.2
Create the Reverse Lookup Zone File
Create the reverse lookup zone file.
bashCopy codesudo nano /etc/bind/db.10.0.0
Add the following content to the file.
pythonCopy code$TTL 604800
@ IN SOA ns1.example.com. admin.example.com. (
2024072101 ; Serial
604800 ; Refresh
86400 ; Retry
2419200 ; Expire
604800 ) ; Negative Cache TTL
;
@ IN NS ns1.example.com.
2 IN PTR server1.example.com.
3. Restart BIND
Restart the BIND service to apply the changes.
bashCopy codesudo systemctl restart bind9
4. Test the Configuration
You can use the dig command to test the reverse DNS setup.
bashCopy codedig -x 10.0.0.2
If everything is set up correctly, the response should include the PTR record pointing to server1.example.com.
Summary
Install BIND.
Edit /etc/bind/named.conf.local to add zone definitions.
Create and configure the forward lookup zone file (/etc/bind/db.example.com).
Create and configure the reverse lookup zone file (/etc/bind/db.10.0.0).
Restart BIND.
Test the setup using dig.
This configuration provides a basic setup for reverse DNS on a private network using BIND on an Ubuntu server.
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