REFERENCE LIBRARY
DNS field guides
Practical notes for the question after the query.
Choose a task, not a guess
Use a command-line reference when you need a reproducible query. Use the record comparison when deciding between an address and an alias. For a browser DNS error, first separate local settings from a public DNS observation.
These guides link back to the corresponding tools. They explain what a result can establish and when more evidence is needed; they do not replace the operating system, DNS provider or mail platform’s own documentation.
Three practical starting points
Using the nslookup command
Query a name, change the record type and specify a resolver from a terminal.
A records vs CNAME records
Understand address records, aliases and why DNS is not an HTTP redirect.
Troubleshoot DNS_PROBE_FINISHED_BAD_CONFIG
Separate a local resolver problem from a public DNS configuration issue.