How to Test DNS Resolver Speed

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Domain Name System (DNS) resolver speed plays a crucial role in determining the responsiveness of your internet browsing experience. A slow DNS can lead to delays in website loading, even if your internet connection is fast. In this article, we’ll show you how to test DNS resolver speed using a DNS server performance test tool, providing you with a ready-to-use Python script and explaining how to interpret the results.

Why Test DNS Speed?

DNS resolvers are responsible for translating human-readable domain names (like example.com) into IP addresses. The speed of this translation impacts how quickly websites load. Testing DNS speed helps you:

  1. Identify the fastest DNS resolver for your network.
  2. Optimize your internet connection for better performance.
  3. Troubleshoot slow browsing issues.

Tools You Need

To test DNS speed, you’ll need:

  • Python installed on your system (version 3.x).
  • The dnspython library for DNS queries.

You can install the dnspython library with the following command:

pip install dnspython

DNS Server Performance Test Tool

Here’s a Python script to measure the speed of multiple DNS resolvers:

import dns.resolver
import time


# List of DNS resolvers to test
dns_resolvers = [
    '8.8.8.8',   # Google Public DNS
    'YourDNS2',  # DNS2
    'YourDNS3',  # DNS2

]

# Preloaded list of 100 domains for testing
test_domains = [
    "example.com", "google.com", "amazon.com", "apple.com", "microsoft.com",
    "facebook.com", "yahoo.com", "wikipedia.org", "github.com", "stackoverflow.com",
    "netflix.com", "reddit.com", "linkedin.com", "bing.com", "quora.com",
]

# Function to test a single resolver for a single domain
def test_resolver_speed(resolver_ip, domain):
    resolver = dns.resolver.Resolver()
    resolver.nameservers = [resolver_ip]
    try:
        start_time = time.time()
        resolver.resolve(domain, "A")
        end_time = time.time()
        return (end_time - start_time) * 1000  # Convert to milliseconds
    except Exception as e:
        return None  # Return None if query fails

# Test all resolvers across all domains
print(f"Testing DNS resolvers across {len(test_domains)} domains...\n")
results = {}

for dns_ip in dns_resolvers:
    total_time = 0
    success_count = 0
    for domain in test_domains:
        response_time = test_resolver_speed(dns_ip, domain)
        if response_time is not None:
            total_time += response_time
            success_count += 1
    average_time = total_time / success_count if success_count > 0 else None
    results[dns_ip] = average_time
    if average_time is not None:
        print(f"{dns_ip}: Average response time: {average_time:.2f} ms ({success_count}/{len(test_domains)} successful queries)")
    else:
        print(f"{dns_ip}: No successful queries")

# Print sorted results
print("\nSorted results (fastest to slowest):")
sorted_results = sorted(results.items(), key=lambda x: x[1] if x[1] is not None else float('inf'))
for dns_ip, average_time in sorted_results:
    if average_time is not None:
        print(f"{dns_ip}: {average_time:.2f} ms")
    else:
        print(f"{dns_ip}: No successful queries")

Check out the DNS resolver speed test script tool code on GitHub.

How the Script Works

  1. DNS Resolver List: Specify the DNS resolvers you want to test.
  2. Domain List: Provide a list of domains for testing. More domains result in more accurate averages.
  3. Response Time Calculation: The script measures the time taken to resolve each domain and calculates the average time for each DNS resolver.
  4. Results Sorting: DNS resolvers are ranked from fastest to slowest based on their average response times.

Interpreting the Results

  • Average Response Time: Lower values indicate faster DNS resolution.
  • Success Rate: A high number of successful queries suggests a reliable resolver.
  • Sorted Results: Use the fastest resolver for better browsing performance.

Key Considerations

  1. Network Conditions: Run the test multiple times to account for network variability.
  2. Resolver Reliability: A resolver with consistent speeds and high reliability is preferable.
  3. Security Features: Consider DNS resolvers with security features like DNSSEC or malware blocking.

Conclusion

Testing DNS resolver speed can significantly improve your internet experience by reducing website loading times. With the Python script provided, you can quickly evaluate different DNS resolvers and choose the best one for your needs. Whether you’re a tech enthusiast or just looking to optimize your browsing, this guide empowers you to take control of your DNS settings.

For more tech tutorials and insights, visit arstech.net.

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