Python: Get the domain name using PTR DNS records from a given IP address

Last update on May 24 2025 10:48:48 (UTC/GMT +8 hours)

PTR DNS Domain Name

Write a Python program to get the domain name using PTR DNS records from a given IP address.

What is a DNS PTR record?

The Domain Name System, or DNS, correlates domain names with IP addresses. A DNS pointer record (PTR for short) provides the domain name associated with an IP address. A DNS PTR record is exactly the opposite of the 'A' record, which provides the IP address associated with a domain name.

DNS PTR records are used in reverse DNS lookups. When a user attempts to reach a domain name in their browser, a DNS lookup occurs, matching the domain name to the IP address. A reverse DNS lookup is the opposite of this process: it is a query that starts with the IP address and looks up the domain name. Source: cloudflare.com

Sample Solution-1:

Python Code:

# Define a function 'get_domain_name' that takes an IP address as an argument.
def get_domain_name(ip_address):
    # Import the 'socket' module to perform DNS queries.
    import socket
    
    # Use 'socket.gethostbyaddr' to get the domain name associated with the given IP address.
    result = socket.gethostbyaddr(ip_address)
    
    # Convert the result to a list and return the first element, which is the domain name.
    return list(result)[0]

# Display a message indicating the next section.
print("Domain name using PTR DNS:")

# Call the 'get_domain_name' function with different IP addresses and print the results.
print(get_domain_name("8.8.8.8"))
print(get_domain_name("13.251.106.90"))
print(get_domain_name("8.8.4.4"))
print(get_domain_name("23.23.212.126"))

Sample Output:

Domain name using PTR DNS:
dns.google
ec2-13-251-106-90.ap-southeast-1.compute.amazonaws.com
dns.google
ec2-23-23-212-126.compute-1.amazonaws.com

Explanation:

Here is a breakdown of the above Python code:

• get_domain_name Function:
• Defines a function "get_domain_name()" that takes an IP address as an argument.
• Importing the 'socket' Module:
• Imports the "socket" module to perform DNS queries.
• Performing DNS Query:
• Uses socket.gethostbyaddr to get the domain name associated with the given IP address.
• Returning the Domain Name:
• Converts the result to a list and returns the first element, which is the domain name.
• Calling the Function:
• Calls the "get_domain_name()" function with different IP addresses and prints the results.

Flowchart:

Sample Solution-2:

Python Code:

# Define a function 'get_domain_name' that takes an IP address as an argument.
def get_domain_name(ip_address):
    # Import the 'socket' module to perform DNS queries.
    import socket
    
    # Use 'socket.getfqdn' to get the fully qualified domain name associated with the given IP address.
    return socket.getfqdn(ip_address)

# Display a message indicating the next section.
print("Domain name using PTR DNS:")

# Call the 'get_domain_name' function with different IP addresses and print the results.
print(get_domain_name("8.8.8.8"))
print(get_domain_name("13.251.106.90"))
print(get_domain_name("8.8.4.4"))
print(get_domain_name("23.23.212.126"))

Sample Output:

Domain name using PTR DNS:
dns.google
ec2-13-251-106-90.ap-southeast-1.compute.amazonaws.com
dns.google
ec2-23-23-212-126.compute-1.amazonaws.com

Explanation:

Here is a breakdown of the above Python code:

• get_domain_name Function:
• Define a function "get_domain_name()" that takes an IP address as an argument.
• Importing the 'socket' module:
• Import the "socket" module to perform DNS queries.
• Performing DNS query:
• Use socket.getfqdn to get the fully qualified domain name associated with the given IP address.
• Return the domain name:
• Returns the fully qualified domain name obtained from the DNS query.
• Call the function:
• Calls the "get_domain_name()" function with different IP addresses and prints the results.

Flowchart:

For more Practice: Solve these Related Problems:

• Write a Python program to perform a reverse DNS lookup for a given IP address and return the associated domain name.
• Write a Python program to query PTR DNS records for an IP address using a DNS library and display the result.
• Write a Python program to retrieve the domain name from an IP address by performing a reverse DNS lookup with socket.gethostbyaddr().
• Write a Python program to get the PTR record for an IP address and output the corresponding domain name.

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