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Caching Tutorial Part 2

The second part of a fairly detailed and interesting presentation of the material relating to the cache and its use. Part 1 .

The author, Mark Nottingham , is a recognized expert in the field of HTTP protocol and web caching. He is chairman of the IETF HTTPbis Working Group . Took part in editing HTTP / 1.1, part. 6: Caching. Currently involved in the development of HTTP / 2.0.

The text is distributed under the Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 Unported License .
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From the translator: about typos and inaccuracies, please report in a personal. Thank.


How (and how not to) manage the cache


There are several tools that web designers and webmasters can use to fine tune how the cache will work with their sites. This may require a little familiarization with the server configuration, but it's worth it. For more detailed information on how to use these tools for working with your server, refer to the “ Implementation ” sections (note of the translator — see the next section) below.

Meta tags HTML and HTTP headers

Professionals working with HTML can place certain tags in the section of the HTML-, . - , .

- , . , , ( HTML-). - - Pragma: no-cache HTML- , .

, HTTP- , , . HTML , , -. , , . , HTTP- , .

HTTP- HTML . HTTP/1.1 :

HTTP/1.1 200 OK
Date: Fri, 30 Oct 1998 13:19:41 GMT
Server: Apache/1.3.3 (Unix)
Cache-Control: max-age=3600, must-revalidate
Expires: Fri, 30 Oct 1998 14:19:41 GMT
Last-Modified: Mon, 29 Jun 1998 02:28:12 GMT
ETag: "3e86-410-3596fbbc"
Content-Length: 1040
Content-Type: text/html

HTML , . “ ” (. - ), , HTTP-.

- (ISP) - HTTP- ( Expires Cache-Control ), ; , .

HTTP- Pragma ( )
, HTTP- Pragma: no-cache . ; HTTP Pragma ; Pragma (, ) . , - , . , .

HTTP- Expires
HTTP- Expires - ; , . , , , . Expires .

- Expires . , ; , , (last access time); , (last modification time).

Expires ( ). , . , . , - , , “”.

, HTTP- HTTP- Expires . - , . , , HTTP- (GMT), .

:
Expires: Fri, 30 Oct 1998 14:19:41 GMT

Expires , . -, - , ; /, .

Expires , , . Expires , , , .

, - , Expires . - ( Network Time Protocol , NTP); .

HTTP- Cache-Control
HTTP/1.1 , Cache-Control , - , Expires .

Cache-Control :
max-age =[] - , . Expires , , , . [] - , , . s-maxage =[] - max-age , , (.. ). public - , ; , HTTP-, . private - , (.. ) ; (.. ) - . no-cache - , . , , ( public ) . no-store - , . must-revalidate - , , . HTTP ; , , , . proxy-revalidate - must-revalidate , , .
:
Cache-Control: max-age=3600, must-revalidate

, Cache-Control , Expires - , Cache-Control . Cache-Control , HTTP/1.1 .


“ ” , , . , , , , .

; ( Expires Cache-Control ), .

, , Last-Modified . , Last-Modified , () , , , If-Modified-Since .

HTTP/1.1 , ETag . ETag - , , . , ETag , , , ETag If-None-Match , .

Last-Modified ; ETag .

- ETag , Last-Modified , (.. ); . , (, CGI, ASP, ), (. “ , ”).


, , , .

URL- - . , , URL-. . , “/index.html” , . . , , Cache-Control: max-age max-age . , , max-age (expiration time). ( ) , . , , ; , , - , . . , Last-Modified . - , , . , . SSL - ; SSL . REDbot - .

,
-, (. - “” , “”) ( Last-Modified ETag ) ( Expires Cache-Control ). - ( , ), (, , ) .

, , (, ), . , URL-, ; , - , .

- , . - , , . , , Last-Modified . - , , , . Expires , Cache-Control: max-age , . , , If-Modified-Since / If-None-Match . HTTP 304 Not Modified . , .
:
POST, . POST- ; ( GET), . , , URL-, . , , . Content-Length . (persistent connection). TCP/IP , . , , .

" " (. - ). HTML-, . - , .

- , . , , ( HTML-). - - Pragma: no-cache HTML- , .

, HTTP- , , . HTML , , -. , , . , HTTP- , .

HTTP- HTML . HTTP/1.1 :

HTTP/1.1 200 OK
Date: Fri, 30 Oct 1998 13:19:41 GMT
Server: Apache/1.3.3 (Unix)
Cache-Control: max-age=3600, must-revalidate
Expires: Fri, 30 Oct 1998 14:19:41 GMT
Last-Modified: Mon, 29 Jun 1998 02:28:12 GMT
ETag: "3e86-410-3596fbbc"
Content-Length: 1040
Content-Type: text/html

HTML , . “ ” (. - ), , HTTP-.

- (ISP) - HTTP- ( Expires Cache-Control ), ; , .

HTTP- Pragma ( )
, HTTP- Pragma: no-cache . ; HTTP Pragma ; Pragma (, ) . , - , . , .

HTTP- Expires
HTTP- Expires - ; , . , , , . Expires .

- Expires . , ; , , (last access time); , (last modification time).

Expires ( ). , . , . , - , , “”.

, HTTP- HTTP- Expires . - , . , , HTTP- (GMT), .

:
Expires: Fri, 30 Oct 1998 14:19:41 GMT

Expires , . -, - , ; /, .

Expires , , . Expires , , , .

, - , Expires . - ( Network Time Protocol , NTP); .

HTTP- Cache-Control
HTTP/1.1 , Cache-Control , - , Expires .

Cache-Control :
max-age =[] - , . Expires , , , . [] - , , . s-maxage =[] - max-age , , (.. ). public - , ; , HTTP-, . private - , (.. ) ; (.. ) - . no-cache - , . , , ( public ) . no-store - , . must-revalidate - , , . HTTP ; , , , . proxy-revalidate - must-revalidate , , .
:
Cache-Control: max-age=3600, must-revalidate

, Cache-Control , Expires - , Cache-Control . Cache-Control , HTTP/1.1 .


“ ” , , . , , , , .

; ( Expires Cache-Control ), .

, , Last-Modified . , Last-Modified , () , , , If-Modified-Since .

HTTP/1.1 , ETag . ETag - , , . , ETag , , , ETag If-None-Match , .

Last-Modified ; ETag .

- ETag , Last-Modified , (.. ); . , (, CGI, ASP, ), (. “ , ”).


, , , .

URL- - . , , URL-. . , “/index.html” , . . , , Cache-Control: max-age max-age . , , max-age (expiration time). ( ) , . , , ; , , - , . . , Last-Modified . - , , . , . SSL - ; SSL . REDbot - .

,
-, (. - “” , “”) ( Last-Modified ETag ) ( Expires Cache-Control ). - ( , ), (, , ) .

, , (, ), . , URL-, ; , - , .

- , . - , , . , , Last-Modified . - , , , . Expires , Cache-Control: max-age , . , , If-Modified-Since / If-None-Match . HTTP 304 Not Modified . , .
:
POST, . POST- ; ( GET), . , , URL-, . , , . Content-Length . (persistent connection). TCP/IP , . , , .

" " (. - ).
HTML-, . - , .

- , . , , ( HTML-). - - Pragma: no-cache HTML- , .

, HTTP- , , . HTML , , -. , , . , HTTP- , .

HTTP- HTML . HTTP/1.1 :

HTTP/1.1 200 OK
Date: Fri, 30 Oct 1998 13:19:41 GMT
Server: Apache/1.3.3 (Unix)
Cache-Control: max-age=3600, must-revalidate
Expires: Fri, 30 Oct 1998 14:19:41 GMT
Last-Modified: Mon, 29 Jun 1998 02:28:12 GMT
ETag: "3e86-410-3596fbbc"
Content-Length: 1040
Content-Type: text/html

HTML , . “ ” (. - ), , HTTP-.

- (ISP) - HTTP- ( Expires Cache-Control ), ; , .

HTTP- Pragma ( )
, HTTP- Pragma: no-cache . ; HTTP Pragma ; Pragma (, ) . , - , . , .

HTTP- Expires
HTTP- Expires - ; , . , , , . Expires .

- Expires . , ; , , (last access time); , (last modification time).

Expires ( ). , . , . , - , , “”.

, HTTP- HTTP- Expires . - , . , , HTTP- (GMT), .

:
Expires: Fri, 30 Oct 1998 14:19:41 GMT

Expires , . -, - , ; /, .

Expires , , . Expires , , , .

, - , Expires . - ( Network Time Protocol , NTP); .

HTTP- Cache-Control
HTTP/1.1 , Cache-Control , - , Expires .

Cache-Control :
max-age =[] - , . Expires , , , . [] - , , . s-maxage =[] - max-age , , (.. ). public - , ; , HTTP-, . private - , (.. ) ; (.. ) - . no-cache - , . , , ( public ) . no-store - , . must-revalidate - , , . HTTP ; , , , . proxy-revalidate - must-revalidate , , .
:
Cache-Control: max-age=3600, must-revalidate

, Cache-Control , Expires - , Cache-Control . Cache-Control , HTTP/1.1 .


“ ” , , . , , , , .

; ( Expires Cache-Control ), .

, , Last-Modified . , Last-Modified , () , , , If-Modified-Since .

HTTP/1.1 , ETag . ETag - , , . , ETag , , , ETag If-None-Match , .

Last-Modified ; ETag .

- ETag , Last-Modified , (.. ); . , (, CGI, ASP, ), (. “ , ”).


, , , .

URL- - . , , URL-. . , “/index.html” , . . , , Cache-Control: max-age max-age . , , max-age (expiration time). ( ) , . , , ; , , - , . . , Last-Modified . - , , . , . SSL - ; SSL . REDbot - .

,
-, (. - “” , “”) ( Last-Modified ETag ) ( Expires Cache-Control ). - ( , ), (, , ) .

, , (, ), . , URL-, ; , - , .

- , . - , , . , , Last-Modified . - , , , . Expires , Cache-Control: max-age , . , , If-Modified-Since / If-None-Match . HTTP 304 Not Modified . , .
:
POST, . POST- ; ( GET), . , , URL-, . , , . Content-Length . (persistent connection). TCP/IP , . , , .

" " (. - ).
HTML-, . - , .

- , . , , ( HTML-). - - Pragma: no-cache HTML- , .

, HTTP- , , . HTML , , -. , , . , HTTP- , .

HTTP- HTML . HTTP/1.1 :

HTTP/1.1 200 OK
Date: Fri, 30 Oct 1998 13:19:41 GMT
Server: Apache/1.3.3 (Unix)
Cache-Control: max-age=3600, must-revalidate
Expires: Fri, 30 Oct 1998 14:19:41 GMT
Last-Modified: Mon, 29 Jun 1998 02:28:12 GMT
ETag: "3e86-410-3596fbbc"
Content-Length: 1040
Content-Type: text/html

HTML , . “ ” (. - ), , HTTP-.

- (ISP) - HTTP- ( Expires Cache-Control ), ; , .

HTTP- Pragma ( )
, HTTP- Pragma: no-cache . ; HTTP Pragma ; Pragma (, ) . , - , . , .

HTTP- Expires
HTTP- Expires - ; , . , , , . Expires .

- Expires . , ; , , (last access time); , (last modification time).

Expires ( ). , . , . , - , , “”.

, HTTP- HTTP- Expires . - , . , , HTTP- (GMT), .

:
Expires: Fri, 30 Oct 1998 14:19:41 GMT

Expires , . -, - , ; /, .

Expires , , . Expires , , , .

, - , Expires . - ( Network Time Protocol , NTP); .

HTTP- Cache-Control
HTTP/1.1 , Cache-Control , - , Expires .

Cache-Control :
max-age =[] - , . Expires , , , . [] - , , . s-maxage =[] - max-age , , (.. ). public - , ; , HTTP-, . private - , (.. ) ; (.. ) - . no-cache - , . , , ( public ) . no-store - , . must-revalidate - , , . HTTP ; , , , . proxy-revalidate - must-revalidate , , .
:
Cache-Control: max-age=3600, must-revalidate

, Cache-Control , Expires - , Cache-Control . Cache-Control , HTTP/1.1 .


“ ” , , . , , , , .

; ( Expires Cache-Control ), .

, , Last-Modified . , Last-Modified , () , , , If-Modified-Since .

HTTP/1.1 , ETag . ETag - , , . , ETag , , , ETag If-None-Match , .

Last-Modified ; ETag .

- ETag , Last-Modified , (.. ); . , (, CGI, ASP, ), (. “ , ”).


, , , .

URL- - . , , URL-. . , “/index.html” , . . , , Cache-Control: max-age max-age . , , max-age (expiration time). ( ) , . , , ; , , - , . . , Last-Modified . - , , . , . SSL - ; SSL . REDbot - .

,
-, (. - “” , “”) ( Last-Modified ETag ) ( Expires Cache-Control ). - ( , ), (, , ) .

, , (, ), . , URL-, ; , - , .

- , . - , , . , , Last-Modified . - , , , . Expires , Cache-Control: max-age , . , , If-Modified-Since / If-None-Match . HTTP 304 Not Modified . , .
:
POST, . POST- ; ( GET), . , , URL-, . , , . Content-Length . (persistent connection). TCP/IP , . , , .

" " (. - ).
HTML-, . - , .

- , . , , ( HTML-). - - Pragma: no-cache HTML- , .

, HTTP- , , . HTML , , -. , , . , HTTP- , .

HTTP- HTML . HTTP/1.1 :

HTTP/1.1 200 OK
Date: Fri, 30 Oct 1998 13:19:41 GMT
Server: Apache/1.3.3 (Unix)
Cache-Control: max-age=3600, must-revalidate
Expires: Fri, 30 Oct 1998 14:19:41 GMT
Last-Modified: Mon, 29 Jun 1998 02:28:12 GMT
ETag: "3e86-410-3596fbbc"
Content-Length: 1040
Content-Type: text/html

HTML , . “ ” (. - ), , HTTP-.

- (ISP) - HTTP- ( Expires Cache-Control ), ; , .

HTTP- Pragma ( )
, HTTP- Pragma: no-cache . ; HTTP Pragma ; Pragma (, ) . , - , . , .

HTTP- Expires
HTTP- Expires - ; , . , , , . Expires .

- Expires . , ; , , (last access time); , (last modification time).

Expires ( ). , . , . , - , , “”.

, HTTP- HTTP- Expires . - , . , , HTTP- (GMT), .

:
Expires: Fri, 30 Oct 1998 14:19:41 GMT

Expires , . -, - , ; /, .

Expires , , . Expires , , , .

, - , Expires . - ( Network Time Protocol , NTP); .

HTTP- Cache-Control
HTTP/1.1 , Cache-Control , - , Expires .

Cache-Control :
max-age =[] - , . Expires , , , . [] - , , . s-maxage =[] - max-age , , (.. ). public - , ; , HTTP-, . private - , (.. ) ; (.. ) - . no-cache - , . , , ( public ) . no-store - , . must-revalidate - , , . HTTP ; , , , . proxy-revalidate - must-revalidate , , .
:
Cache-Control: max-age=3600, must-revalidate

, Cache-Control , Expires - , Cache-Control . Cache-Control , HTTP/1.1 .


“ ” , , . , , , , .

; ( Expires Cache-Control ), .

, , Last-Modified . , Last-Modified , () , , , If-Modified-Since .

HTTP/1.1 , ETag . ETag - , , . , ETag , , , ETag If-None-Match , .

Last-Modified ; ETag .

- ETag , Last-Modified , (.. ); . , (, CGI, ASP, ), (. “ , ”).


, , , .

URL- - . , , URL-. . , “/index.html” , . . , , Cache-Control: max-age max-age . , , max-age (expiration time). ( ) , . , , ; , , - , . . , Last-Modified . - , , . , . SSL - ; SSL . REDbot - .

,
-, (. - “” , “”) ( Last-Modified ETag ) ( Expires Cache-Control ). - ( , ), (, , ) .

, , (, ), . , URL-, ; , - , .

- , . - , , . , , Last-Modified . - , , , . Expires , Cache-Control: max-age , . , , If-Modified-Since / If-None-Match . HTTP 304 Not Modified . , .
:
POST, . POST- ; ( GET), . , , URL-, . , , . Content-Length . (persistent connection). TCP/IP , . , , .

" " (. - ).
HTML-, . - , .

- , . , , ( HTML-). - - Pragma: no-cache HTML- , .

, HTTP- , , . HTML , , -. , , . , HTTP- , .

HTTP- HTML . HTTP/1.1 :

HTTP/1.1 200 OK
Date: Fri, 30 Oct 1998 13:19:41 GMT
Server: Apache/1.3.3 (Unix)
Cache-Control: max-age=3600, must-revalidate
Expires: Fri, 30 Oct 1998 14:19:41 GMT
Last-Modified: Mon, 29 Jun 1998 02:28:12 GMT
ETag: "3e86-410-3596fbbc"
Content-Length: 1040
Content-Type: text/html

HTML , . “ ” (. - ), , HTTP-.

- (ISP) - HTTP- ( Expires Cache-Control ), ; , .

HTTP- Pragma ( )
, HTTP- Pragma: no-cache . ; HTTP Pragma ; Pragma (, ) . , - , . , .

HTTP- Expires
HTTP- Expires - ; , . , , , . Expires .

- Expires . , ; , , (last access time); , (last modification time).

Expires ( ). , . , . , - , , “”.

, HTTP- HTTP- Expires . - , . , , HTTP- (GMT), .

:
Expires: Fri, 30 Oct 1998 14:19:41 GMT

Expires , . -, - , ; /, .

Expires , , . Expires , , , .

, - , Expires . - ( Network Time Protocol , NTP); .

HTTP- Cache-Control
HTTP/1.1 , Cache-Control , - , Expires .

Cache-Control :
max-age =[] - , . Expires , , , . [] - , , . s-maxage =[] - max-age , , (.. ). public - , ; , HTTP-, . private - , (.. ) ; (.. ) - . no-cache - , . , , ( public ) . no-store - , . must-revalidate - , , . HTTP ; , , , . proxy-revalidate - must-revalidate , , .
:
Cache-Control: max-age=3600, must-revalidate

, Cache-Control , Expires - , Cache-Control . Cache-Control , HTTP/1.1 .


“ ” , , . , , , , .

; ( Expires Cache-Control ), .

, , Last-Modified . , Last-Modified , () , , , If-Modified-Since .

HTTP/1.1 , ETag . ETag - , , . , ETag , , , ETag If-None-Match , .

Last-Modified ; ETag .

- ETag , Last-Modified , (.. ); . , (, CGI, ASP, ), (. “ , ”).


, , , .

URL- - . , , URL-. . , “/index.html” , . . , , Cache-Control: max-age max-age . , , max-age (expiration time). ( ) , . , , ; , , - , . . , Last-Modified . - , , . , . SSL - ; SSL . REDbot - .

,
-, (. - “” , “”) ( Last-Modified ETag ) ( Expires Cache-Control ). - ( , ), (, , ) .

, , (, ), . , URL-, ; , - , .

- , . - , , . , , Last-Modified . - , , , . Expires , Cache-Control: max-age , . , , If-Modified-Since / If-None-Match . HTTP 304 Not Modified . , .
:
POST, . POST- ; ( GET), . , , URL-, . , , . Content-Length . (persistent connection). TCP/IP , . , , .

" " (. - ).
HTML-, . - , .

- , . , , ( HTML-). - - Pragma: no-cache HTML- , .

, HTTP- , , . HTML , , -. , , . , HTTP- , .

HTTP- HTML . HTTP/1.1 :

HTTP/1.1 200 OK
Date: Fri, 30 Oct 1998 13:19:41 GMT
Server: Apache/1.3.3 (Unix)
Cache-Control: max-age=3600, must-revalidate
Expires: Fri, 30 Oct 1998 14:19:41 GMT
Last-Modified: Mon, 29 Jun 1998 02:28:12 GMT
ETag: "3e86-410-3596fbbc"
Content-Length: 1040
Content-Type: text/html

HTML , . “ ” (. - ), , HTTP-.

- (ISP) - HTTP- ( Expires Cache-Control ), ; , .

HTTP- Pragma ( )
, HTTP- Pragma: no-cache . ; HTTP Pragma ; Pragma (, ) . , - , . , .

HTTP- Expires
HTTP- Expires - ; , . , , , . Expires .

- Expires . , ; , , (last access time); , (last modification time).

Expires ( ). , . , . , - , , “”.

, HTTP- HTTP- Expires . - , . , , HTTP- (GMT), .

:
Expires: Fri, 30 Oct 1998 14:19:41 GMT

Expires , . -, - , ; /, .

Expires , , . Expires , , , .

, - , Expires . - ( Network Time Protocol , NTP); .

HTTP- Cache-Control
HTTP/1.1 , Cache-Control , - , Expires .

Cache-Control :
max-age =[] - , . Expires , , , . [] - , , . s-maxage =[] - max-age , , (.. ). public - , ; , HTTP-, . private - , (.. ) ; (.. ) - . no-cache - , . , , ( public ) . no-store - , . must-revalidate - , , . HTTP ; , , , . proxy-revalidate - must-revalidate , , .
:
Cache-Control: max-age=3600, must-revalidate

, Cache-Control , Expires - , Cache-Control . Cache-Control , HTTP/1.1 .


“ ” , , . , , , , .

; ( Expires Cache-Control ), .

, , Last-Modified . , Last-Modified , () , , , If-Modified-Since .

HTTP/1.1 , ETag . ETag - , , . , ETag , , , ETag If-None-Match , .

Last-Modified ; ETag .

- ETag , Last-Modified , (.. ); . , (, CGI, ASP, ), (. “ , ”).


, , , .

URL- - . , , URL-. . , “/index.html” , . . , , Cache-Control: max-age max-age . , , max-age (expiration time). ( ) , . , , ; , , - , . . , Last-Modified . - , , . , . SSL - ; SSL . REDbot - .

,
-, (. - “” , “”) ( Last-Modified ETag ) ( Expires Cache-Control ). - ( , ), (, , ) .

, , (, ), . , URL-, ; , - , .

- , . - , , . , , Last-Modified . - , , , . Expires , Cache-Control: max-age , . , , If-Modified-Since / If-None-Match . HTTP 304 Not Modified . , .
:
POST, . POST- ; ( GET), . , , URL-, . , , . Content-Length . (persistent connection). TCP/IP , . , , .

" " (. - ).
HTML-, . - , .

- , . , , ( HTML-). - - Pragma: no-cache HTML- , .

, HTTP- , , . HTML , , -. , , . , HTTP- , .

HTTP- HTML . HTTP/1.1 :

HTTP/1.1 200 OK
Date: Fri, 30 Oct 1998 13:19:41 GMT
Server: Apache/1.3.3 (Unix)
Cache-Control: max-age=3600, must-revalidate
Expires: Fri, 30 Oct 1998 14:19:41 GMT
Last-Modified: Mon, 29 Jun 1998 02:28:12 GMT
ETag: "3e86-410-3596fbbc"
Content-Length: 1040
Content-Type: text/html

HTML , . “ ” (. - ), , HTTP-.

- (ISP) - HTTP- ( Expires Cache-Control ), ; , .

HTTP- Pragma ( )
, HTTP- Pragma: no-cache . ; HTTP Pragma ; Pragma (, ) . , - , . , .

HTTP- Expires
HTTP- Expires - ; , . , , , . Expires .

- Expires . , ; , , (last access time); , (last modification time).

Expires ( ). , . , . , - , , “”.

, HTTP- HTTP- Expires . - , . , , HTTP- (GMT), .

:
Expires: Fri, 30 Oct 1998 14:19:41 GMT

Expires , . -, - , ; /, .

Expires , , . Expires , , , .

, - , Expires . - ( Network Time Protocol , NTP); .

HTTP- Cache-Control
HTTP/1.1 , Cache-Control , - , Expires .

Cache-Control :
max-age =[] - , . Expires , , , . [] - , , . s-maxage =[] - max-age , , (.. ). public - , ; , HTTP-, . private - , (.. ) ; (.. ) - . no-cache - , . , , ( public ) . no-store - , . must-revalidate - , , . HTTP ; , , , . proxy-revalidate - must-revalidate , , .
:
Cache-Control: max-age=3600, must-revalidate

, Cache-Control , Expires - , Cache-Control . Cache-Control , HTTP/1.1 .


“ ” , , . , , , , .

; ( Expires Cache-Control ), .

, , Last-Modified . , Last-Modified , () , , , If-Modified-Since .

HTTP/1.1 , ETag . ETag - , , . , ETag , , , ETag If-None-Match , .

Last-Modified ; ETag .

- ETag , Last-Modified , (.. ); . , (, CGI, ASP, ), (. “ , ”).


, , , .

URL- - . , , URL-. . , “/index.html” , . . , , Cache-Control: max-age max-age . , , max-age (expiration time). ( ) , . , , ; , , - , . . , Last-Modified . - , , . , . SSL - ; SSL . REDbot - .

,
-, (. - “” , “”) ( Last-Modified ETag ) ( Expires Cache-Control ). - ( , ), (, , ) .

, , (, ), . , URL-, ; , - , .

- , . - , , . , , Last-Modified . - , , , . Expires , Cache-Control: max-age , . , , If-Modified-Since / If-None-Match . HTTP 304 Not Modified . , .
:
POST, . POST- ; ( GET), . , , URL-, . , , . Content-Length . (persistent connection). TCP/IP , . , , .

" " (. - ).
HTML-, . - , .

- , . , , ( HTML-). - - Pragma: no-cache HTML- , .

, HTTP- , , . HTML , , -. , , . , HTTP- , .

HTTP- HTML . HTTP/1.1 :

HTTP/1.1 200 OK
Date: Fri, 30 Oct 1998 13:19:41 GMT
Server: Apache/1.3.3 (Unix)
Cache-Control: max-age=3600, must-revalidate
Expires: Fri, 30 Oct 1998 14:19:41 GMT
Last-Modified: Mon, 29 Jun 1998 02:28:12 GMT
ETag: "3e86-410-3596fbbc"
Content-Length: 1040
Content-Type: text/html

HTML , . “ ” (. - ), , HTTP-.

- (ISP) - HTTP- ( Expires Cache-Control ), ; , .

HTTP- Pragma ( )
, HTTP- Pragma: no-cache . ; HTTP Pragma ; Pragma (, ) . , - , . , .

HTTP- Expires
HTTP- Expires - ; , . , , , . Expires .

- Expires . , ; , , (last access time); , (last modification time).

Expires ( ). , . , . , - , , “”.

, HTTP- HTTP- Expires . - , . , , HTTP- (GMT), .

:
Expires: Fri, 30 Oct 1998 14:19:41 GMT

Expires , . -, - , ; /, .

Expires , , . Expires , , , .

, - , Expires . - ( Network Time Protocol , NTP); .

HTTP- Cache-Control
HTTP/1.1 , Cache-Control , - , Expires .

Cache-Control :
max-age =[] - , . Expires , , , . [] - , , . s-maxage =[] - max-age , , (.. ). public - , ; , HTTP-, . private - , (.. ) ; (.. ) - . no-cache - , . , , ( public ) . no-store - , . must-revalidate - , , . HTTP ; , , , . proxy-revalidate - must-revalidate , , .
:
Cache-Control: max-age=3600, must-revalidate

, Cache-Control , Expires - , Cache-Control . Cache-Control , HTTP/1.1 .


“ ” , , . , , , , .

; ( Expires Cache-Control ), .

, , Last-Modified . , Last-Modified , () , , , If-Modified-Since .

HTTP/1.1 , ETag . ETag - , , . , ETag , , , ETag If-None-Match , .

Last-Modified ; ETag .

- ETag , Last-Modified , (.. ); . , (, CGI, ASP, ), (. “ , ”).


, , , .

URL- - . , , URL-. . , “/index.html” , . . , , Cache-Control: max-age max-age . , , max-age (expiration time). ( ) , . , , ; , , - , . . , Last-Modified . - , , . , . SSL - ; SSL . REDbot - .

,
-, (. - “” , “”) ( Last-Modified ETag ) ( Expires Cache-Control ). - ( , ), (, , ) .

, , (, ), . , URL-, ; , - , .

- , . - , , . , , Last-Modified . - , , , . Expires , Cache-Control: max-age , . , , If-Modified-Since / If-None-Match . HTTP 304 Not Modified . , .
:
POST, . POST- ; ( GET), . , , URL-, . , , . Content-Length . (persistent connection). TCP/IP , . , , .

" " (. - ).
HTML-, . - , .

- , . , , ( HTML-). - - Pragma: no-cache HTML- , .

, HTTP- , , . HTML , , -. , , . , HTTP- , .

HTTP- HTML . HTTP/1.1 :

HTTP/1.1 200 OK
Date: Fri, 30 Oct 1998 13:19:41 GMT
Server: Apache/1.3.3 (Unix)
Cache-Control: max-age=3600, must-revalidate
Expires: Fri, 30 Oct 1998 14:19:41 GMT
Last-Modified: Mon, 29 Jun 1998 02:28:12 GMT
ETag: "3e86-410-3596fbbc"
Content-Length: 1040
Content-Type: text/html

HTML , . “ ” (. - ), , HTTP-.

- (ISP) - HTTP- ( Expires Cache-Control ), ; , .

HTTP- Pragma ( )
, HTTP- Pragma: no-cache . ; HTTP Pragma ; Pragma (, ) . , - , . , .

HTTP- Expires
HTTP- Expires - ; , . , , , . Expires .

- Expires . , ; , , (last access time); , (last modification time).

Expires ( ). , . , . , - , , “”.

, HTTP- HTTP- Expires . - , . , , HTTP- (GMT), .

:
Expires: Fri, 30 Oct 1998 14:19:41 GMT

Expires , . -, - , ; /, .

Expires , , . Expires , , , .

, - , Expires . - ( Network Time Protocol , NTP); .

HTTP- Cache-Control
HTTP/1.1 , Cache-Control , - , Expires .

Cache-Control :
max-age =[] - , . Expires , , , . [] - , , . s-maxage =[] - max-age , , (.. ). public - , ; , HTTP-, . private - , (.. ) ; (.. ) - . no-cache - , . , , ( public ) . no-store - , . must-revalidate - , , . HTTP ; , , , . proxy-revalidate - must-revalidate , , .
:
Cache-Control: max-age=3600, must-revalidate

, Cache-Control , Expires - , Cache-Control . Cache-Control , HTTP/1.1 .


“ ” , , . , , , , .

; ( Expires Cache-Control ), .

, , Last-Modified . , Last-Modified , () , , , If-Modified-Since .

HTTP/1.1 , ETag . ETag - , , . , ETag , , , ETag If-None-Match , .

Last-Modified ; ETag .

- ETag , Last-Modified , (.. ); . , (, CGI, ASP, ), (. “ , ”).


, , , .

URL- - . , , URL-. . , “/index.html” , . . , , Cache-Control: max-age max-age . , , max-age (expiration time). ( ) , . , , ; , , - , . . , Last-Modified . - , , . , . SSL - ; SSL . REDbot - .

,
-, (. - “” , “”) ( Last-Modified ETag ) ( Expires Cache-Control ). - ( , ), (, , ) .

, , (, ), . , URL-, ; , - , .

- , . - , , . , , Last-Modified . - , , , . Expires , Cache-Control: max-age , . , , If-Modified-Since / If-None-Match . HTTP 304 Not Modified . , .
:
POST, . POST- ; ( GET), . , , URL-, . , , . Content-Length . (persistent connection). TCP/IP , . , , .

" " (. - ).
HTML-, . - , .

- , . , , ( HTML-). - - Pragma: no-cache HTML- , .

, HTTP- , , . HTML , , -. , , . , HTTP- , .

HTTP- HTML . HTTP/1.1 :

HTTP/1.1 200 OK
Date: Fri, 30 Oct 1998 13:19:41 GMT
Server: Apache/1.3.3 (Unix)
Cache-Control: max-age=3600, must-revalidate
Expires: Fri, 30 Oct 1998 14:19:41 GMT
Last-Modified: Mon, 29 Jun 1998 02:28:12 GMT
ETag: "3e86-410-3596fbbc"
Content-Length: 1040
Content-Type: text/html

HTML , . “ ” (. - ), , HTTP-.

- (ISP) - HTTP- ( Expires Cache-Control ), ; , .

HTTP- Pragma ( )
, HTTP- Pragma: no-cache . ; HTTP Pragma ; Pragma (, ) . , - , . , .

HTTP- Expires
HTTP- Expires - ; , . , , , . Expires .

- Expires . , ; , , (last access time); , (last modification time).

Expires ( ). , . , . , - , , “”.

, HTTP- HTTP- Expires . - , . , , HTTP- (GMT), .

:
Expires: Fri, 30 Oct 1998 14:19:41 GMT

Expires , . -, - , ; /, .

Expires , , . Expires , , , .

, - , Expires . - ( Network Time Protocol , NTP); .

HTTP- Cache-Control
HTTP/1.1 , Cache-Control , - , Expires .

Cache-Control :
max-age =[] - , . Expires , , , . [] - , , . s-maxage =[] - max-age , , (.. ). public - , ; , HTTP-, . private - , (.. ) ; (.. ) - . no-cache - , . , , ( public ) . no-store - , . must-revalidate - , , . HTTP ; , , , . proxy-revalidate - must-revalidate , , .
:
Cache-Control: max-age=3600, must-revalidate

, Cache-Control , Expires - , Cache-Control . Cache-Control , HTTP/1.1 .


“ ” , , . , , , , .

; ( Expires Cache-Control ), .

, , Last-Modified . , Last-Modified , () , , , If-Modified-Since .

HTTP/1.1 , ETag . ETag - , , . , ETag , , , ETag If-None-Match , .

Last-Modified ; ETag .

- ETag , Last-Modified , (.. ); . , (, CGI, ASP, ), (. “ , ”).


, , , .

URL- - . , , URL-. . , “/index.html” , . . , , Cache-Control: max-age max-age . , , max-age (expiration time). ( ) , . , , ; , , - , . . , Last-Modified . - , , . , . SSL - ; SSL . REDbot - .

,
-, (. - “” , “”) ( Last-Modified ETag ) ( Expires Cache-Control ). - ( , ), (, , ) .

, , (, ), . , URL-, ; , - , .

- , . - , , . , , Last-Modified . - , , , . Expires , Cache-Control: max-age , . , , If-Modified-Since / If-None-Match . HTTP 304 Not Modified . , .
:
POST, . POST- ; ( GET), . , , URL-, . , , . Content-Length . (persistent connection). TCP/IP , . , , .

" " (. - ).
HTML-, . - , .

- , . , , ( HTML-). - - Pragma: no-cache HTML- , .

, HTTP- , , . HTML , , -. , , . , HTTP- , .

HTTP- HTML . HTTP/1.1 :

HTTP/1.1 200 OK
Date: Fri, 30 Oct 1998 13:19:41 GMT
Server: Apache/1.3.3 (Unix)
Cache-Control: max-age=3600, must-revalidate
Expires: Fri, 30 Oct 1998 14:19:41 GMT
Last-Modified: Mon, 29 Jun 1998 02:28:12 GMT
ETag: "3e86-410-3596fbbc"
Content-Length: 1040
Content-Type: text/html

HTML , . “ ” (. - ), , HTTP-.

- (ISP) - HTTP- ( Expires Cache-Control ), ; , .

HTTP- Pragma ( )
, HTTP- Pragma: no-cache . ; HTTP Pragma ; Pragma (, ) . , - , . , .

HTTP- Expires
HTTP- Expires - ; , . , , , . Expires .

- Expires . , ; , , (last access time); , (last modification time).

Expires ( ). , . , . , - , , “”.

, HTTP- HTTP- Expires . - , . , , HTTP- (GMT), .

:
Expires: Fri, 30 Oct 1998 14:19:41 GMT

Expires , . -, - , ; /, .

Expires , , . Expires , , , .

, - , Expires . - ( Network Time Protocol , NTP); .

HTTP- Cache-Control
HTTP/1.1 , Cache-Control , - , Expires .

Cache-Control :
max-age =[] - , . Expires , , , . [] - , , . s-maxage =[] - max-age , , (.. ). public - , ; , HTTP-, . private - , (.. ) ; (.. ) - . no-cache - , . , , ( public ) . no-store - , . must-revalidate - , , . HTTP ; , , , . proxy-revalidate - must-revalidate , , .
:
Cache-Control: max-age=3600, must-revalidate

, Cache-Control , Expires - , Cache-Control . Cache-Control , HTTP/1.1 .


“ ” , , . , , , , .

; ( Expires Cache-Control ), .

, , Last-Modified . , Last-Modified , () , , , If-Modified-Since .

HTTP/1.1 , ETag . ETag - , , . , ETag , , , ETag If-None-Match , .

Last-Modified ; ETag .

- ETag , Last-Modified , (.. ); . , (, CGI, ASP, ), (. “ , ”).


, , , .

URL- - . , , URL-. . , “/index.html” , . . , , Cache-Control: max-age max-age . , , max-age (expiration time). ( ) , . , , ; , , - , . . , Last-Modified . - , , . , . SSL - ; SSL . REDbot - .

,
-, (. - “” , “”) ( Last-Modified ETag ) ( Expires Cache-Control ). - ( , ), (, , ) .

, , (, ), . , URL-, ; , - , .

- , . - , , . , , Last-Modified . - , , , . Expires , Cache-Control: max-age , . , , If-Modified-Since / If-None-Match . HTTP 304 Not Modified . , .
:
POST, . POST- ; ( GET), . , , URL-, . , , . Content-Length . (persistent connection). TCP/IP , . , , .

" " (. - ).HTML-, . - , .

- , . , , ( HTML-). - - Pragma: no-cache HTML- , .

, HTTP- , , . HTML , , -. , , . , HTTP- , .

HTTP- HTML . HTTP/1.1 :

HTTP/1.1 200 OK
Date: Fri, 30 Oct 1998 13:19:41 GMT
Server: Apache/1.3.3 (Unix)
Cache-Control: max-age=3600, must-revalidate
Expires: Fri, 30 Oct 1998 14:19:41 GMT
Last-Modified: Mon, 29 Jun 1998 02:28:12 GMT
ETag: "3e86-410-3596fbbc"
Content-Length: 1040
Content-Type: text/html

HTML , . “ ” (. - ), , HTTP-.

- (ISP) - HTTP- ( Expires Cache-Control ), ; , .

HTTP- Pragma ( )
, HTTP- Pragma: no-cache . ; HTTP Pragma ; Pragma (, ) . , - , . , .

HTTP- Expires
HTTP- Expires - ; , . , , , . Expires .

- Expires . , ; , , (last access time); , (last modification time).

Expires ( ). , . , . , - , , “”.

, HTTP- HTTP- Expires . - , . , , HTTP- (GMT), .

:
Expires: Fri, 30 Oct 1998 14:19:41 GMT

Expires , . -, - , ; /, .

Expires , , . Expires , , , .

, - , Expires . - ( Network Time Protocol , NTP); .

HTTP- Cache-Control
HTTP/1.1 , Cache-Control , - , Expires .

Cache-Control :
max-age =[] - , . Expires , , , . [] - , , . s-maxage =[] - max-age , , (.. ). public - , ; , HTTP-, . private - , (.. ) ; (.. ) - . no-cache - , . , , ( public ) . no-store - , . must-revalidate - , , . HTTP ; , , , . proxy-revalidate - must-revalidate , , .
:
Cache-Control: max-age=3600, must-revalidate

, Cache-Control , Expires - , Cache-Control . Cache-Control , HTTP/1.1 .


“ ” , , . , , , , .

; ( Expires Cache-Control ), .

, , Last-Modified . , Last-Modified , () , , , If-Modified-Since .

HTTP/1.1 , ETag . ETag - , , . , ETag , , , ETag If-None-Match , .

Last-Modified ; ETag .

- ETag , Last-Modified , (.. ); . , (, CGI, ASP, ), (. “ , ”).


, , , .

URL- - . , , URL-. . , “/index.html” , . . , , Cache-Control: max-age max-age . , , max-age (expiration time). ( ) , . , , ; , , - , . . , Last-Modified . - , , . , . SSL - ; SSL . REDbot - .

,
-, (. - “” , “”) ( Last-Modified ETag ) ( Expires Cache-Control ). - ( , ), (, , ) .

, , (, ), . , URL-, ; , - , .

- , . - , , . , , Last-Modified . - , , , . Expires , Cache-Control: max-age , . , , If-Modified-Since / If-None-Match . HTTP 304 Not Modified . , .
:
POST, . POST- ; ( GET), . , , URL-, . , , . Content-Length . (persistent connection). TCP/IP , . , , .

" " (. - ).
HTML-, . - , .

- , . , , ( HTML-). - - Pragma: no-cache HTML- , .

, HTTP- , , . HTML , , -. , , . , HTTP- , .

HTTP- HTML . HTTP/1.1 :

HTTP/1.1 200 OK
Date: Fri, 30 Oct 1998 13:19:41 GMT
Server: Apache/1.3.3 (Unix)
Cache-Control: max-age=3600, must-revalidate
Expires: Fri, 30 Oct 1998 14:19:41 GMT
Last-Modified: Mon, 29 Jun 1998 02:28:12 GMT
ETag: "3e86-410-3596fbbc"
Content-Length: 1040
Content-Type: text/html

HTML , . “ ” (. - ), , HTTP-.

- (ISP) - HTTP- ( Expires Cache-Control ), ; , .

HTTP- Pragma ( )
, HTTP- Pragma: no-cache . ; HTTP Pragma ; Pragma (, ) . , - , . , .

HTTP- Expires
HTTP- Expires - ; , . , , , . Expires .

- Expires . , ; , , (last access time); , (last modification time).

Expires ( ). , . , . , - , , “”.

, HTTP- HTTP- Expires . - , . , , HTTP- (GMT), .

:
Expires: Fri, 30 Oct 1998 14:19:41 GMT

Expires , . -, - , ; /, .

Expires , , . Expires , , , .

, - , Expires . - ( Network Time Protocol , NTP); .

HTTP- Cache-Control
HTTP/1.1 , Cache-Control , - , Expires .

Cache-Control :
max-age =[] - , . Expires , , , . [] - , , . s-maxage =[] - max-age , , (.. ). public - , ; , HTTP-, . private - , (.. ) ; (.. ) - . no-cache - , . , , ( public ) . no-store - , . must-revalidate - , , . HTTP ; , , , . proxy-revalidate - must-revalidate , , .
:
Cache-Control: max-age=3600, must-revalidate

, Cache-Control , Expires - , Cache-Control . Cache-Control , HTTP/1.1 .


“ ” , , . , , , , .

; ( Expires Cache-Control ), .

, , Last-Modified . , Last-Modified , () , , , If-Modified-Since .

HTTP/1.1 , ETag . ETag - , , . , ETag , , , ETag If-None-Match , .

Last-Modified ; ETag .

- ETag , Last-Modified , (.. ); . , (, CGI, ASP, ), (. “ , ”).


, , , .

URL- - . , , URL-. . , “/index.html” , . . , , Cache-Control: max-age max-age . , , max-age (expiration time). ( ) , . , , ; , , - , . . , Last-Modified . - , , . , . SSL - ; SSL . REDbot - .

,
-, (. - “” , “”) ( Last-Modified ETag ) ( Expires Cache-Control ). - ( , ), (, , ) .

, , (, ), . , URL-, ; , - , .

- , . - , , . , , Last-Modified . - , , , . Expires , Cache-Control: max-age , . , , If-Modified-Since / If-None-Match . HTTP 304 Not Modified . , .
:
POST, . POST- ; ( GET), . , , URL-, . , , . Content-Length . (persistent connection). TCP/IP , . , , .

" " (. - ).
HTML-, . - , .

- , . , , ( HTML-). - - Pragma: no-cache HTML- , .

, HTTP- , , . HTML , , -. , , . , HTTP- , .

HTTP- HTML . HTTP/1.1 :

HTTP/1.1 200 OK
Date: Fri, 30 Oct 1998 13:19:41 GMT
Server: Apache/1.3.3 (Unix)
Cache-Control: max-age=3600, must-revalidate
Expires: Fri, 30 Oct 1998 14:19:41 GMT
Last-Modified: Mon, 29 Jun 1998 02:28:12 GMT
ETag: "3e86-410-3596fbbc"
Content-Length: 1040
Content-Type: text/html

HTML , . “ ” (. - ), , HTTP-.

- (ISP) - HTTP- ( Expires Cache-Control ), ; , .

HTTP- Pragma ( )
, HTTP- Pragma: no-cache . ; HTTP Pragma ; Pragma (, ) . , - , . , .

HTTP- Expires
HTTP- Expires - ; , . , , , . Expires .

- Expires . , ; , , (last access time); , (last modification time).

Expires ( ). , . , . , - , , “”.

, HTTP- HTTP- Expires . - , . , , HTTP- (GMT), .

:
Expires: Fri, 30 Oct 1998 14:19:41 GMT

Expires , . -, - , ; /, .

Expires , , . Expires , , , .

, - , Expires . - ( Network Time Protocol , NTP); .

HTTP- Cache-Control
HTTP/1.1 , Cache-Control , - , Expires .

Cache-Control :
max-age =[] - , . Expires , , , . [] - , , . s-maxage =[] - max-age , , (.. ). public - , ; , HTTP-, . private - , (.. ) ; (.. ) - . no-cache - , . , , ( public ) . no-store - , . must-revalidate - , , . HTTP ; , , , . proxy-revalidate - must-revalidate , , .
:
Cache-Control: max-age=3600, must-revalidate

, Cache-Control , Expires - , Cache-Control . Cache-Control , HTTP/1.1 .


“ ” , , . , , , , .

; ( Expires Cache-Control ), .

, , Last-Modified . , Last-Modified , () , , , If-Modified-Since .

HTTP/1.1 , ETag . ETag - , , . , ETag , , , ETag If-None-Match , .

Last-Modified ; ETag .

- ETag , Last-Modified , (.. ); . , (, CGI, ASP, ), (. “ , ”).


, , , .

URL- - . , , URL-. . , “/index.html” , . . , , Cache-Control: max-age max-age . , , max-age (expiration time). ( ) , . , , ; , , - , . . , Last-Modified . - , , . , . SSL - ; SSL . REDbot - .

,
-, (. - “” , “”) ( Last-Modified ETag ) ( Expires Cache-Control ). - ( , ), (, , ) .

, , (, ), . , URL-, ; , - , .

- , . - , , . , , Last-Modified . - , , , . Expires , Cache-Control: max-age , . , , If-Modified-Since / If-None-Match . HTTP 304 Not Modified . , .
:
POST, . POST- ; ( GET), . , , URL-, . , , . Content-Length . (persistent connection). TCP/IP , . , , .

" " (. - ).

HTML-, . - , .

- , . , , ( HTML-). - - Pragma: no-cache HTML- , .

, HTTP- , , . HTML , , -. , , . , HTTP- , .

HTTP- HTML . HTTP/1.1 :

HTTP/1.1 200 OK
Date: Fri, 30 Oct 1998 13:19:41 GMT
Server: Apache/1.3.3 (Unix)
Cache-Control: max-age=3600, must-revalidate
Expires: Fri, 30 Oct 1998 14:19:41 GMT
Last-Modified: Mon, 29 Jun 1998 02:28:12 GMT
ETag: "3e86-410-3596fbbc"
Content-Length: 1040
Content-Type: text/html

HTML , . “ ” (. - ), , HTTP-.

- (ISP) - HTTP- ( Expires Cache-Control ), ; , .

HTTP- Pragma ( )
, HTTP- Pragma: no-cache . ; HTTP Pragma ; Pragma (, ) . , - , . , .

HTTP- Expires
HTTP- Expires - ; , . , , , . Expires .

- Expires . , ; , , (last access time); , (last modification time).

Expires ( ). , . , . , - , , “”.

, HTTP- HTTP- Expires . - , . , , HTTP- (GMT), .

:
Expires: Fri, 30 Oct 1998 14:19:41 GMT

Expires , . -, - , ; /, .

Expires , , . Expires , , , .

, - , Expires . - ( Network Time Protocol , NTP); .

HTTP- Cache-Control
HTTP/1.1 , Cache-Control , - , Expires .

Cache-Control :
max-age =[] - , . Expires , , , . [] - , , . s-maxage =[] - max-age , , (.. ). public - , ; , HTTP-, . private - , (.. ) ; (.. ) - . no-cache - , . , , ( public ) . no-store - , . must-revalidate - , , . HTTP ; , , , . proxy-revalidate - must-revalidate , , .
:
Cache-Control: max-age=3600, must-revalidate

, Cache-Control , Expires - , Cache-Control . Cache-Control , HTTP/1.1 .


“ ” , , . , , , , .

; ( Expires Cache-Control ), .

, , Last-Modified . , Last-Modified , () , , , If-Modified-Since .

HTTP/1.1 , ETag . ETag - , , . , ETag , , , ETag If-None-Match , .

Last-Modified ; ETag .

- ETag , Last-Modified , (.. ); . , (, CGI, ASP, ), (. “ , ”).


, , , .

URL- - . , , URL-. . , “/index.html” , . . , , Cache-Control: max-age max-age . , , max-age (expiration time). ( ) , . , , ; , , - , . . , Last-Modified . - , , . , . SSL - ; SSL . REDbot - .

,
-, (. - “” , “”) ( Last-Modified ETag ) ( Expires Cache-Control ). - ( , ), (, , ) .

, , (, ), . , URL-, ; , - , .

- , . - , , . , , Last-Modified . - , , , . Expires , Cache-Control: max-age , . , , If-Modified-Since / If-None-Match . HTTP 304 Not Modified . , .
:
POST, . POST- ; ( GET), . , , URL-, . , , . Content-Length . (persistent connection). TCP/IP , . , , .

" " (. - ).

HTML-, . - , .

- , . , , ( HTML-). - - Pragma: no-cache HTML- , .

, HTTP- , , . HTML , , -. , , . , HTTP- , .

HTTP- HTML . HTTP/1.1 :

HTTP/1.1 200 OK
Date: Fri, 30 Oct 1998 13:19:41 GMT
Server: Apache/1.3.3 (Unix)
Cache-Control: max-age=3600, must-revalidate
Expires: Fri, 30 Oct 1998 14:19:41 GMT
Last-Modified: Mon, 29 Jun 1998 02:28:12 GMT
ETag: "3e86-410-3596fbbc"
Content-Length: 1040
Content-Type: text/html

HTML , . “ ” (. - ), , HTTP-.

- (ISP) - HTTP- ( Expires Cache-Control ), ; , .

HTTP- Pragma ( )
, HTTP- Pragma: no-cache . ; HTTP Pragma ; Pragma (, ) . , - , . , .

HTTP- Expires
HTTP- Expires - ; , . , , , . Expires .

- Expires . , ; , , (last access time); , (last modification time).

Expires ( ). , . , . , - , , “”.

, HTTP- HTTP- Expires . - , . , , HTTP- (GMT), .

:
Expires: Fri, 30 Oct 1998 14:19:41 GMT

Expires , . -, - , ; /, .

Expires , , . Expires , , , .

, - , Expires . - ( Network Time Protocol , NTP); .

HTTP- Cache-Control
HTTP/1.1 , Cache-Control , - , Expires .

Cache-Control :
max-age =[] - , . Expires , , , . [] - , , . s-maxage =[] - max-age , , (.. ). public - , ; , HTTP-, . private - , (.. ) ; (.. ) - . no-cache - , . , , ( public ) . no-store - , . must-revalidate - , , . HTTP ; , , , . proxy-revalidate - must-revalidate , , .
:
Cache-Control: max-age=3600, must-revalidate

, Cache-Control , Expires - , Cache-Control . Cache-Control , HTTP/1.1 .


“ ” , , . , , , , .

; ( Expires Cache-Control ), .

, , Last-Modified . , Last-Modified , () , , , If-Modified-Since .

HTTP/1.1 , ETag . ETag - , , . , ETag , , , ETag If-None-Match , .

Last-Modified ; ETag .

- ETag , Last-Modified , (.. ); . , (, CGI, ASP, ), (. “ , ”).


, , , .

URL- - . , , URL-. . , “/index.html” , . . , , Cache-Control: max-age max-age . , , max-age (expiration time). ( ) , . , , ; , , - , . . , Last-Modified . - , , . , . SSL - ; SSL . REDbot - .

,
-, (. - “” , “”) ( Last-Modified ETag ) ( Expires Cache-Control ). - ( , ), (, , ) .

, , (, ), . , URL-, ; , - , .

- , . - , , . , , Last-Modified . - , , , . Expires , Cache-Control: max-age , . , , If-Modified-Since / If-None-Match . HTTP 304 Not Modified . , .
:
POST, . POST- ; ( GET), . , , URL-, . , , . Content-Length . (persistent connection). TCP/IP , . , , .

" " (. - ).HTML-, . - , .

- , . , , ( HTML-). - - Pragma: no-cache HTML- , .

, HTTP- , , . HTML , , -. , , . , HTTP- , .

HTTP- HTML . HTTP/1.1 :

HTTP/1.1 200 OK
Date: Fri, 30 Oct 1998 13:19:41 GMT
Server: Apache/1.3.3 (Unix)
Cache-Control: max-age=3600, must-revalidate
Expires: Fri, 30 Oct 1998 14:19:41 GMT
Last-Modified: Mon, 29 Jun 1998 02:28:12 GMT
ETag: "3e86-410-3596fbbc"
Content-Length: 1040
Content-Type: text/html

HTML , . “ ” (. - ), , HTTP-.

- (ISP) - HTTP- ( Expires Cache-Control ), ; , .

HTTP- Pragma ( )
, HTTP- Pragma: no-cache . ; HTTP Pragma ; Pragma (, ) . , - , . , .

HTTP- Expires
HTTP- Expires - ; , . , , , . Expires .

- Expires . , ; , , (last access time); , (last modification time).

Expires ( ). , . , . , - , , “”.

, HTTP- HTTP- Expires . - , . , , HTTP- (GMT), .

:
Expires: Fri, 30 Oct 1998 14:19:41 GMT

Expires , . -, - , ; /, .

Expires , , . Expires , , , .

, - , Expires . - ( Network Time Protocol , NTP); .

HTTP- Cache-Control
HTTP/1.1 , Cache-Control , - , Expires .

Cache-Control :
max-age =[] - , . Expires , , , . [] - , , . s-maxage =[] - max-age , , (.. ). public - , ; , HTTP-, . private - , (.. ) ; (.. ) - . no-cache - , . , , ( public ) . no-store - , . must-revalidate - , , . HTTP ; , , , . proxy-revalidate - must-revalidate , , .
:
Cache-Control: max-age=3600, must-revalidate

, Cache-Control , Expires - , Cache-Control . Cache-Control , HTTP/1.1 .


“ ” , , . , , , , .

; ( Expires Cache-Control ), .

, , Last-Modified . , Last-Modified , () , , , If-Modified-Since .

HTTP/1.1 , ETag . ETag - , , . , ETag , , , ETag If-None-Match , .

Last-Modified ; ETag .

- ETag , Last-Modified , (.. ); . , (, CGI, ASP, ), (. “ , ”).


, , , .

URL- - . , , URL-. . , “/index.html” , . . , , Cache-Control: max-age max-age . , , max-age (expiration time). ( ) , . , , ; , , - , . . , Last-Modified . - , , . , . SSL - ; SSL . REDbot - .

,
-, (. - “” , “”) ( Last-Modified ETag ) ( Expires Cache-Control ). - ( , ), (, , ) .

, , (, ), . , URL-, ; , - , .

- , . - , , . , , Last-Modified . - , , , . Expires , Cache-Control: max-age , . , , If-Modified-Since / If-None-Match . HTTP 304 Not Modified . , .
:
POST, . POST- ; ( GET), . , , URL-, . , , . Content-Length . (persistent connection). TCP/IP , . , , .

" " (. - ).

HTML-, . - , .

- , . , , ( HTML-). - - Pragma: no-cache HTML- , .

, HTTP- , , . HTML , , -. , , . , HTTP- , .

HTTP- HTML . HTTP/1.1 :

HTTP/1.1 200 OK
Date: Fri, 30 Oct 1998 13:19:41 GMT
Server: Apache/1.3.3 (Unix)
Cache-Control: max-age=3600, must-revalidate
Expires: Fri, 30 Oct 1998 14:19:41 GMT
Last-Modified: Mon, 29 Jun 1998 02:28:12 GMT
ETag: "3e86-410-3596fbbc"
Content-Length: 1040
Content-Type: text/html

HTML , . “ ” (. - ), , HTTP-.

- (ISP) - HTTP- ( Expires Cache-Control ), ; , .

HTTP- Pragma ( )
, HTTP- Pragma: no-cache . ; HTTP Pragma ; Pragma (, ) . , - , . , .

HTTP- Expires
HTTP- Expires - ; , . , , , . Expires .

- Expires . , ; , , (last access time); , (last modification time).

Expires ( ). , . , . , - , , “”.

, HTTP- HTTP- Expires . - , . , , HTTP- (GMT), .

:
Expires: Fri, 30 Oct 1998 14:19:41 GMT

Expires , . -, - , ; /, .

Expires , , . Expires , , , .

, - , Expires . - ( Network Time Protocol , NTP); .

HTTP- Cache-Control
HTTP/1.1 , Cache-Control , - , Expires .

Cache-Control :
max-age =[] - , . Expires , , , . [] - , , . s-maxage =[] - max-age , , (.. ). public - , ; , HTTP-, . private - , (.. ) ; (.. ) - . no-cache - , . , , ( public ) . no-store - , . must-revalidate - , , . HTTP ; , , , . proxy-revalidate - must-revalidate , , .
:
Cache-Control: max-age=3600, must-revalidate

, Cache-Control , Expires - , Cache-Control . Cache-Control , HTTP/1.1 .


“ ” , , . , , , , .

; ( Expires Cache-Control ), .

, , Last-Modified . , Last-Modified , () , , , If-Modified-Since .

HTTP/1.1 , ETag . ETag - , , . , ETag , , , ETag If-None-Match , .

Last-Modified ; ETag .

- ETag , Last-Modified , (.. ); . , (, CGI, ASP, ), (. “ , ”).


, , , .

URL- - . , , URL-. . , “/index.html” , . . , , Cache-Control: max-age max-age . , , max-age (expiration time). ( ) , . , , ; , , - , . . , Last-Modified . - , , . , . SSL - ; SSL . REDbot - .

,
-, (. - “” , “”) ( Last-Modified ETag ) ( Expires Cache-Control ). - ( , ), (, , ) .

, , (, ), . , URL-, ; , - , .

- , . - , , . , , Last-Modified . - , , , . Expires , Cache-Control: max-age , . , , If-Modified-Since / If-None-Match . HTTP 304 Not Modified . , .
:
POST, . POST- ; ( GET), . , , URL-, . , , . Content-Length . (persistent connection). TCP/IP , . , , .

" " (. - ).

HTML-, . - , .

- , . , , ( HTML-). - - Pragma: no-cache HTML- , .

, HTTP- , , . HTML , , -. , , . , HTTP- , .

HTTP- HTML . HTTP/1.1 :

HTTP/1.1 200 OK
Date: Fri, 30 Oct 1998 13:19:41 GMT
Server: Apache/1.3.3 (Unix)
Cache-Control: max-age=3600, must-revalidate
Expires: Fri, 30 Oct 1998 14:19:41 GMT
Last-Modified: Mon, 29 Jun 1998 02:28:12 GMT
ETag: "3e86-410-3596fbbc"
Content-Length: 1040
Content-Type: text/html

HTML , . “ ” (. - ), , HTTP-.

- (ISP) - HTTP- ( Expires Cache-Control ), ; , .

HTTP- Pragma ( )
, HTTP- Pragma: no-cache . ; HTTP Pragma ; Pragma (, ) . , - , . , .

HTTP- Expires
HTTP- Expires - ; , . , , , . Expires .

- Expires . , ; , , (last access time); , (last modification time).

Expires ( ). , . , . , - , , “”.

, HTTP- HTTP- Expires . - , . , , HTTP- (GMT), .

:
Expires: Fri, 30 Oct 1998 14:19:41 GMT

Expires , . -, - , ; /, .

Expires , , . Expires , , , .

, - , Expires . - ( Network Time Protocol , NTP); .

HTTP- Cache-Control
HTTP/1.1 , Cache-Control , - , Expires .

Cache-Control :
max-age =[] - , . Expires , , , . [] - , , . s-maxage =[] - max-age , , (.. ). public - , ; , HTTP-, . private - , (.. ) ; (.. ) - . no-cache - , . , , ( public ) . no-store - , . must-revalidate - , , . HTTP ; , , , . proxy-revalidate - must-revalidate , , .
:
Cache-Control: max-age=3600, must-revalidate

, Cache-Control , Expires - , Cache-Control . Cache-Control , HTTP/1.1 .


“ ” , , . , , , , .

; ( Expires Cache-Control ), .

, , Last-Modified . , Last-Modified , () , , , If-Modified-Since .

HTTP/1.1 , ETag . ETag - , , . , ETag , , , ETag If-None-Match , .

Last-Modified ; ETag .

- ETag , Last-Modified , (.. ); . , (, CGI, ASP, ), (. “ , ”).


, , , .

URL- - . , , URL-. . , “/index.html” , . . , , Cache-Control: max-age max-age . , , max-age (expiration time). ( ) , . , , ; , , - , . . , Last-Modified . - , , . , . SSL - ; SSL . REDbot - .

,
-, (. - “” , “”) ( Last-Modified ETag ) ( Expires Cache-Control ). - ( , ), (, , ) .

, , (, ), . , URL-, ; , - , .

- , . - , , . , , Last-Modified . - , , , . Expires , Cache-Control: max-age , . , , If-Modified-Since / If-None-Match . HTTP 304 Not Modified . , .
:
POST, . POST- ; ( GET), . , , URL-, . , , . Content-Length . (persistent connection). TCP/IP , . , , .

" " (. - ).HTML-, . - , .

- , . , , ( HTML-). - - Pragma: no-cache HTML- , .

, HTTP- , , . HTML , , -. , , . , HTTP- , .

HTTP- HTML . HTTP/1.1 :

HTTP/1.1 200 OK
Date: Fri, 30 Oct 1998 13:19:41 GMT
Server: Apache/1.3.3 (Unix)
Cache-Control: max-age=3600, must-revalidate
Expires: Fri, 30 Oct 1998 14:19:41 GMT
Last-Modified: Mon, 29 Jun 1998 02:28:12 GMT
ETag: "3e86-410-3596fbbc"
Content-Length: 1040
Content-Type: text/html

HTML , . “ ” (. - ), , HTTP-.

- (ISP) - HTTP- ( Expires Cache-Control ), ; , .

HTTP- Pragma ( )
, HTTP- Pragma: no-cache . ; HTTP Pragma ; Pragma (, ) . , - , . , .

HTTP- Expires
HTTP- Expires - ; , . , , , . Expires .

- Expires . , ; , , (last access time); , (last modification time).

Expires ( ). , . , . , - , , “”.

, HTTP- HTTP- Expires . - , . , , HTTP- (GMT), .

:
Expires: Fri, 30 Oct 1998 14:19:41 GMT

Expires , . -, - , ; /, .

Expires , , . Expires , , , .

, - , Expires . - ( Network Time Protocol , NTP); .

HTTP- Cache-Control
HTTP/1.1 , Cache-Control , - , Expires .

Cache-Control :
max-age =[] - , . Expires , , , . [] - , , . s-maxage =[] - max-age , , (.. ). public - , ; , HTTP-, . private - , (.. ) ; (.. ) - . no-cache - , . , , ( public ) . no-store - , . must-revalidate - , , . HTTP ; , , , . proxy-revalidate - must-revalidate , , .
:
Cache-Control: max-age=3600, must-revalidate

, Cache-Control , Expires - , Cache-Control . Cache-Control , HTTP/1.1 .


“ ” , , . , , , , .

; ( Expires Cache-Control ), .

, , Last-Modified . , Last-Modified , () , , , If-Modified-Since .

HTTP/1.1 , ETag . ETag - , , . , ETag , , , ETag If-None-Match , .

Last-Modified ; ETag .

- ETag , Last-Modified , (.. ); . , (, CGI, ASP, ), (. “ , ”).


, , , .

URL- - . , , URL-. . , “/index.html” , . . , , Cache-Control: max-age max-age . , , max-age (expiration time). ( ) , . , , ; , , - , . . , Last-Modified . - , , . , . SSL - ; SSL . REDbot - .

,
-, (. - “” , “”) ( Last-Modified ETag ) ( Expires Cache-Control ). - ( , ), (, , ) .

, , (, ), . , URL-, ; , - , .

- , . - , , . , , Last-Modified . - , , , . Expires , Cache-Control: max-age , . , , If-Modified-Since / If-None-Match . HTTP 304 Not Modified . , .
:
POST, . POST- ; ( GET), . , , URL-, . , , . Content-Length . (persistent connection). TCP/IP , . , , .

" " (. - ).HTML-, . - , .

- , . , , ( HTML-). - - Pragma: no-cache HTML- , .

, HTTP- , , . HTML , , -. , , . , HTTP- , .

HTTP- HTML . HTTP/1.1 :

HTTP/1.1 200 OK
Date: Fri, 30 Oct 1998 13:19:41 GMT
Server: Apache/1.3.3 (Unix)
Cache-Control: max-age=3600, must-revalidate
Expires: Fri, 30 Oct 1998 14:19:41 GMT
Last-Modified: Mon, 29 Jun 1998 02:28:12 GMT
ETag: "3e86-410-3596fbbc"
Content-Length: 1040
Content-Type: text/html

HTML , . “ ” (. - ), , HTTP-.

- (ISP) - HTTP- ( Expires Cache-Control ), ; , .

HTTP- Pragma ( )
, HTTP- Pragma: no-cache . ; HTTP Pragma ; Pragma (, ) . , - , . , .

HTTP- Expires
HTTP- Expires - ; , . , , , . Expires .

- Expires . , ; , , (last access time); , (last modification time).

Expires ( ). , . , . , - , , “”.

, HTTP- HTTP- Expires . - , . , , HTTP- (GMT), .

:
Expires: Fri, 30 Oct 1998 14:19:41 GMT

Expires , . -, - , ; /, .

Expires , , . Expires , , , .

, - , Expires . - ( Network Time Protocol , NTP); .

HTTP- Cache-Control
HTTP/1.1 , Cache-Control , - , Expires .

Cache-Control :
max-age =[] - , . Expires , , , . [] - , , . s-maxage =[] - max-age , , (.. ). public - , ; , HTTP-, . private - , (.. ) ; (.. ) - . no-cache - , . , , ( public ) . no-store - , . must-revalidate - , , . HTTP ; , , , . proxy-revalidate - must-revalidate , , .
:
Cache-Control: max-age=3600, must-revalidate

, Cache-Control , Expires - , Cache-Control . Cache-Control , HTTP/1.1 .


“ ” , , . , , , , .

; ( Expires Cache-Control ), .

, , Last-Modified . , Last-Modified , () , , , If-Modified-Since .

HTTP/1.1 , ETag . ETag - , , . , ETag , , , ETag If-None-Match , .

Last-Modified ; ETag .

- ETag , Last-Modified , (.. ); . , (, CGI, ASP, ), (. “ , ”).


, , , .

URL- - . , , URL-. . , “/index.html” , . . , , Cache-Control: max-age max-age . , , max-age (expiration time). ( ) , . , , ; , , - , . . , Last-Modified . - , , . , . SSL - ; SSL . REDbot - .

,
-, (. - “” , “”) ( Last-Modified ETag ) ( Expires Cache-Control ). - ( , ), (, , ) .

, , (, ), . , URL-, ; , - , .

- , . - , , . , , Last-Modified . - , , , . Expires , Cache-Control: max-age , . , , If-Modified-Since / If-None-Match . HTTP 304 Not Modified . , .
:
POST, . POST- ; ( GET), . , , URL-, . , , . Content-Length . (persistent connection). TCP/IP , . , , .

" " (. - ).

Source: https://habr.com/ru/post/204464/

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