The DNS section contains documentation about the DNS (Domain Name System) client implementation in NET. This section is helpful for developers who need a deeper understanding of how DNS works and how .NET applications can leverage the built-in DNS client functionality.
Table of Contents
DNS section documentation
DNS name resolution process – How .NET performs DNS lookups to resolve hostnames to IP addresses. It involves the DNS cache, resolver, and name server protocols.
DNS classes – The DNS and IPHostEntry classes for working with DNS programmatically in .NET code. Methods for lookups, cache access, etc.
DNS record types – Explain common record types like A, AAAA, CNAME, MX, etc., and how .NET represents them.
DNS configuration – Files and configuration options configure the DNS client behavior, like host files, DNS settings in Network adapters, etc.
Name resolution API – Low-level DNS client API for performing queries, updates, and other operations directly against DNS servers.
DNS client events – Events exposed for monitoring DNS client activities like cache updates or name resolution failures.
DNS client internals – Underlying implementation details of the DNS client, like threading, caching strategies, and dependency on the Windows DNS API.
How To Perform A DNS Lookup Using The DNS Class In .NET
- Use the DNS.GetHostEntry method to perform a DNS lookup for www.google.com
- The returned IPHostEntry object contains details like hostname and IP addresses
- It displays the hostname and iterates through the IPAddress list
Methods DNS Class Provide For DNS Lookups
GetHostByName(string hostName) – Performs a forward lookup of an IPv4 address from a hostname.
GetHostEntry(string hostNameOrAddress) – Generic version that takes a hostname or IP address.
GetHostAddresses(string hostNameOrAddress) – Gets just the IPAddress list without other host details.
GetHostName() – Performs a reverse lookup on the local machine’s IP address.
GetHostAddressesAsync(string host) – asynchronous version of GetHostAddresses.
GetHostEntryAsync(string host) – asynchronous version of GetHostEntry.
Resolve(string host) – Resolves hostname to an IPHost, resolves a namespaced host.
ResolveAsync(string host) – Async version of Resolve.
GetRecords(string host, RecordType type) – Gets specific DNS record types.
Query(string host, QueryType type) – Low-level query for any DNS record type.
GetMXRecords(string domain) – Gets mail exchange records for a part.
GetSrvRecords(string name, string protocol, string service) – Gets SRV records.
How To Use The Gethostbyname Method
- Call Dns.GetHostByName, passing the hostname as a string
- It performs a forward DNS lookup to resolve the IP addresses
- The IPHostEntry returned contains the hostname and IPAddress list
- We display the hostname and iterate the address list
Conclusion
The # DNS section comprehensively overviews how the DNS client works within .NET applications. It offers valuable insight into the resolution process, available APIs, and key configuration options. This level of documentation helps developers better understand and leverage the built-in DNS functionality. The coverage of classes like DNS and IPHostEntry, common record types, and low-level query methods empowers programmers to integrate robust DNS functionality into their systems.