DNS Client Program (Python 3.12)

Contributors

Created by Marc-Antoine Nadeau and Karl Bridi

Description

This Python program implements a DNS client software. It was developed and tested using Python 3.12.

This DNS client is capable of sending queries for:

• A records (IP addresses)
• MX records (mail server)
• NS records (name server) And interpreting responses for:
• A records
• CNAME records

The program is responsible for:

• Parsing the user input (if the program is invoked from the command line/stdin)
• Sending queries to the server for the domain name using UDP sockets
• Receiving the response from the server (and resending other queries if needed)
• Interpreting the response form the server and outputing the result to the terminal display (stdout if the program is invoked from the command line)

How to Run

1. Navigate to the src folder:

cd src

2. To execute a DNS request, use the following command:

python dnsClient.py [-t timeout] [-r max-retries] [-p port] [-mx | -ns] @serverIPV4 domainName 

• timeout: (Optional) How long to wait, in seconds, before retransmitting an unanswered query. Default value: 5.
• max-retries: (Optional) The maximum number of retry attempts. Default value: 3.
• port: (Optional) The UDP port number of the DNS server. Default value: 53.
• -mx | -ns flags: (Optional) Indicates either to send a MX (Mail server) or NS (Name Server) query. At most one of these can be given, and If neither is given then the client should a type A (IP Address) query.
• @serverIPV4: (Required) The IPv4 address of the DNS server, in a.b.c.d. format.
• domainName: (Required) The domain name to query for.

Example

    python dnsClient.py -t 5 -r 3 -p 53 -ns @8.8.8.8 mcgill.ca