Term Kind Topic What it is
DNS Resolution Chain concept DNS The sequence of lookups from browser cache through OS cache, recursive resolver, root, TLD and authoritative server that turns a name into an address.
DNS TTL concept DNS The time a DNS record may be cached, and a value that resolvers, operating systems and applications honour inconsistently.
DNS TTL Strategy practice DNS Choosing record lifetimes to balance failover speed against query volume, knowing that resolvers and clients do not reliably honour them.