Bulk Reverse DNS Lookup

ip addresses: Paste anyting. We will catch the first 500 valid ips.

or upload as file:

choose file max 20MB

Server: must be ipv4

Do not show unnecessary fields on table
Hide “name”, “rdata”, “type”, “ttl”, “rdlength” and “class” in results.

Strict Query Mode
strict query mode means that if the hostname that was looked up isn’t actually in the answer section of the response, script will return an empty answer section, instead of an answer section that could contain CNAME records.

Recurse
if we should set the recursion desired bit to 1 or 0.

Dnssec
request DNSSEC values, by setting the DO flag to 1; this actually makes the resolver add a OPT RR to the additional section, and sets the DO flag in this RR to 1.

Dnssec Ad Flag
set the DNSSEC AD (Authentic Data) bit on/off.

Dnssec Cd Flag
set the DNSSEC CD (Checking Disabled) bit on/off

What is Reverse DNS and what does it do?

Reverse DNS (rDNS) is a method of DNS (Domain Name System) resolution wherein IP addresses are mapped to domain names, the opposite of the usual forward DNS process which converts domain names into IP addresses. This technique is critical for many network services and security protocols, playing a significant role in reducing spam, improving internet security, and facilitating network troubleshooting. This article delves into the concept, operation, and applications of reverse DNS, providing insights into its significance in the digital world.

Understanding Reverse DNS

Reverse DNS lookup is akin to looking up a phone number in a reverse phone directory to find out who it belongs to. In the context of the internet, it translates numerical IP addresses back to human-readable domain names. This process is managed through a special domain in the DNS system known as the "in-addr.arpa" domain for IPv4, and "ip6.arpa" for IPv6 addresses.

How Reverse DNS Works

The operation of reverse DNS starts with a reverse DNS zone, which, unlike forward DNS, maps parts of IP addresses to domain names. When a reverse DNS lookup is performed, the querying DNS server sends a request to the DNS server responsible for the IP address in question. If properly configured, the server responds with the PTR (pointer) record that contains the domain name associated with the IP address.

Applications of Reverse DNS

Email Security: Reverse DNS lookups are widely used to combat email spam. Email servers can use rDNS to verify that the IP address of an incoming email matches the domain name claimed by the sender. This verification helps to block emails from known spammers or improperly configured servers.
Network Troubleshooting: rDNS can be helpful in diagnosing network issues. By resolving IP addresses to domain names, network administrators can more easily identify devices and troubleshoot problems.
Logging and Reporting: Logs and reports are more understandable when they contain domain names instead of just IP addresses. Reverse DNS lookups facilitate this translation, making it easier for administrators to read and interpret data.
Web and Content Delivery: Some web services use reverse DNS to direct users to content in their geographic location, improving load times and user experience.

Challenges and Considerations

While reverse DNS can be incredibly useful, it comes with its own set of challenges. Not all IP addresses have PTR records, and the absence of a reverse DNS entry can sometimes cause legitimate emails to be marked as spam or lead to other communication issues. Additionally, maintaining reverse DNS records requires effort and coordination between domain owners and their hosting or internet service providers.

Conclusion

Reverse DNS is a fundamental aspect of the DNS system, providing an essential service for security, network management, and more. Its role in validating email sources, aiding in network diagnostics, and enhancing user experiences cannot be overstated. Despite its challenges, the benefits of reverse DNS make it a crucial tool for administrators and a key component of a secure, efficient internet.

Bulk Reverse DNS Lookup