Also called address record
A record, explained
Each A record holds one IPv4 address; a name can have several for redundancy, and the IPv6 equivalent is the AAAA record. Resolvers cache records for their TTL, so a change can take minutes or hours to reach every visitor. The bare domain, example.com rather than www.example.com, cannot hold a CNAME under DNS rules, so it usually carries A records, though some DNS hosts offer alias or flattened records as a workaround.
For an investor, A records decide where a name's visitors land. To show a for-sale page or parking, you either switch the nameservers to the marketplace or parking service, or keep your own DNS host and set the A record they supply, which leaves email and other records under your control. Review records on names you buy and names you retire: an A record pointing to a server or cloud address you no longer control can send your visitors to whoever holds that address next.
Example. To show a for-sale page while keeping email where it was, the owner changed only the A record for the bare domain to the address the lander service supplied.
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