Network Programming and DNS

ECSE 316 | Assignment 1 | Julien Heng, Sophia Li

Run the Program

This program was written and tested with Python version 3.9.6.

How to Run

The program should be invoked at the command line. The command is structured as follows:

python3 dnsClient.py [-t timeout] [-r max-retries] [-p port] [-mx|-ns] @server name

• timeout (optional) gives how long to wait, in seconds, before retransmitting an unanswered query. Default value: 5.
• max-retries (optional) is the maximum number of times to retransmit an unanswered query before giving up. Default value: 3.
• port (optional) is the UDP port number of the DNS server. Default value: 53.
• -mx or -ns flags (optional) indicate whether 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 send a type A (IP address) query.
• server (required) is the IPv4 address of the DNS server, in a.b.c.d. format.
• name (required) is the domain name to query for.

Sample Commands

Query for www.mcgill.ca IP address using the McGill DNS server:

python3 dnsClient.py @132.206.85.18 www.mcgill.ca

Query for the mcgill.ca mail server using Google’s public DNS server with a timeout of 10 seconds and at most 2 retries:

python3 dnsClient.py -t 10 -r 2 -mx @8.8.8.8 mcgill.ca