Last-Modified (HTTP header)
E736181
Last-Modified is an HTTP response header that indicates the date and time at which the origin server believes the requested resource was last changed, enabling caching and conditional requests.
Observed surface forms (1)
| Surface form | Occurrences |
|---|---|
| Last-Modified | 0 |
Statements (47)
| Predicate | Object |
|---|---|
| instanceOf | HTTP response header field ⓘ |
| actsAs | weak validator ⓘ |
| appliesTo |
resource state
ⓘ
selected representation ⓘ |
| canBe | strong validator ⓘ |
| canBeOmittedWhen |
resource is known to change frequently
ⓘ
server cannot determine modification time ⓘ |
| category | response header ⓘ |
| comparisonGranularity | one-second resolution ⓘ |
| definedIn |
RFC 7232
NERFINISHED
ⓘ
RFC 9110 NERFINISHED ⓘ |
| enables |
304 Not Modified responses
ⓘ
conditional GET ⓘ conditional HEAD ⓘ |
| exampleValue | Last-Modified: Wed, 21 Oct 2015 07:28:00 GMT ⓘ |
| format | HTTP-date ⓘ |
| hasFieldName | Last-Modified ⓘ |
| headerSection | response header section ⓘ |
| indicates | date and time the origin server believes the selected representation was last modified ⓘ |
| influences |
cache freshness validation
ⓘ
revalidation policy ⓘ |
| interactsWith |
Cache-Control
ⓘ
Expires ⓘ |
| mayDifferFrom | actual last modification time on origin server ⓘ |
| mustNotBeInFuture | relative to server time ⓘ |
| notAllowedIn | HTTP request headers ⓘ |
| partOf | Hypertext Transfer Protocol NERFINISHED ⓘ |
| relatedTo |
ETag
ⓘ
If-Modified-Since ⓘ If-Unmodified-Since ⓘ Last-Modified validator ⓘ |
| replacedSpecification | RFC 2616 ⓘ |
| securityConsideration | can reveal information about resource change history ⓘ |
| semantics | representation metadata ⓘ |
| setBy | origin server ⓘ |
| status | standard HTTP header ⓘ |
| timeZoneRequirement | GMT NERFINISHED ⓘ |
| usedBy |
caches
ⓘ
intermediaries ⓘ user agents ⓘ |
| usedFor |
HTTP caching
ⓘ
avoiding unnecessary data transfer ⓘ bandwidth optimization ⓘ cache revalidation ⓘ conditional requests ⓘ |
| usedIn |
HTTP/1.0
ⓘ
HTTP/1.1 NERFINISHED ⓘ |
Referenced by (1)
Full triples — surface form annotated when it differs from this entity's canonical label.