maxCacheTTL

maxcachettl, often written as “max‑cache‑TTL” or “maxCacheTTL”, is a configuration parameter that defines the longest period that cached data may be considered valid before it must be refreshed or discarded. The term “TTL” stands for time‑to‑live, a concept used in many caching, networking, and content‑delivery contexts to limit the lifespan of stored information and to ensure that clients receive up‑to‑date data.

In web and HTTP caching, maxcachettl is applied to responses that lack explicit expiration headers. When a server or proxy sets a maxcachettl value, it imposes an upper bound on the freshness lifetime of such responses, preventing stale content from persisting indefinitely. Similar functionality appears in DNS resolvers, where a maxcachettl setting caps the duration that negative or positive DNS records may be cached, overriding the TTL specified by authoritative name servers when that value exceeds the configured maximum.

Application‑level caches, such as those in programming frameworks or content‑delivery networks, also expose a maxcachettl option. Administrators use it to balance performance gains from cached data against the risk of serving outdated information. Typical defaults range from a few minutes to several hours, depending on the system’s intended workload and the volatility of the underlying data.

Setting maxcachettl too low can lead to increased load on origin servers and higher latency, while excessively high values may cause consistency problems and stale content delivery. Best practice recommends aligning the maxcachettl with the expected update frequency of the cached resources, and, where possible, honoring explicit TTLs supplied by data sources. Related parameters include mincachettl (the minimum freshness period) and cachecontrol directives that provide more granular cache management.