defaultTtl property
Specifies the default TTL for cached content served by this origin for responses that do not have an existing valid TTL (max-age or s-max-age).
Setting a TTL of "0" means "always revalidate". The value of defaultTTL cannot be set to a value greater than that of maxTTL, but can be equal. When the cacheMode is set to FORCE_CACHE_ALL, the defaultTTL will overwrite the TTL set in all responses. The maximum allowed value is 31,622,400s (1 year), noting that infrequently accessed objects may be evicted from the cache before the defined TTL.
Implementation
core.int? defaultTtl;