Python uses asyncio to implement asynchronous DNS resolution and caching

Environmental construction and preparation work: 1. Ensure that Python 3.7 and above are installed in the system. 2. Install the "aiodns" library in the Python environment for asynchronous DNS resolution operations. You can install using the following command: pip install aiodns Dependent class libraries: -Asyncio: a module of Python Standard library, used to write asynchronous code. -AIODNS: An asynchronous DNS resolution library based on asyncio. Sample code: python import asyncio import aiodns dns_cache = {} async def resolve_dns(hostname): loop = asyncio.get_event_loop() resolver = aiodns.DNSResolver(loop=loop) if hostname in dns_cache: return dns_cache[hostname] try: response = await resolver.query(hostname, 'A') ip_address = response[0].host dns_cache[hostname] = ip_address return ip_address except aiodns.error.DNSError as e: print(f"DNS resolution failed for {hostname}: {str(e)}") raise e async def main(): hostname = 'example.com' ip_address = await resolve_dns(hostname) print(f"IP address for {hostname} is {ip_address}") if __name__ == '__main__': asyncio.run(main()) Explanation: Firstly, the necessary libraries were imported, including asyncio and aiodns. 2. Created a global DNS_ A cache dictionary is used to cache the corresponding relationships between resolved host names and IP addresses. 3. Resolve defined_ The dns function takes a host name as a parameter and returns the corresponding IP address. First, check the DNS_ Does the cache result already exist for the host name in the cache dictionary? If so, the cache value is directly returned. Otherwise, use the aiodns library for DNS resolution operations and store the results in DNS_ Cache dictionary and return. 4. A main function main is defined, in which resolve is called_ The DNS function obtains the IP address corresponding to the host name and prints the result. 5. Use the asyncio. run() function to run the main function. Summary: By using the asyncio and aiodns libraries, asynchronous DNS parsing and caching operations can be easily implemented. Asynchronous DNS resolution can improve program efficiency and response speed, while caching mechanism can avoid repeatedly resolving the same host name.