A records are the leaf nodes of DNS. Every hostname that resolves to an actual server eventually ends at an A record (for IPv4) or a AAAA record (for IPv6); CNAMEs are just indirection on the way there. A records are simple: name, TTL, record type, address. Multiple A records on the same name are legal and common — returning several IPs for round-robin load balancing or anycast routing, letting clients and resolvers pick one. TTL matters operationally because changing the IP of a record requires either waiting for the TTL to expire everywhere (TTL=86400 means a full day of staleness) or pre-lowering TTL before the change (set TTL=300, wait 24 hours for the low TTL to propagate, then make the change, then raise TTL back). Apex records (`example.com` without a subdomain) must be A or AAAA in standard DNS because CNAMEs are disallowed at the apex, which is why managed DNS providers invented `ALIAS` records to imitate apex CNAME behavior for services that want to abstract their underlying IPs.