General Information

374 단어·2 분·원문(.md)

From: User agent's email information
Referer: Previous web page address
User-Agent: User agent application information
Server: Software information of the origin server processing the request
Date: Date the message was generated

From #

User agent's email information

Generally not widely used
Primarily used by search engines, etc.
Used in requests

Referer #

Previous web page address

The address of the previous web page for the currently requested page
When navigating from A to B, the request for B includes Referer: A
Referer can be used to analyze traffic sources
Used in requests
Note: "referer" is a misspelling of "referrer"

User-Agent #

User agent application information

user-agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36(KHTML, like Gecko) Chrome/86.0.4240.183 Safari/537.36
Client's application information (web browser information, etc.)
Statistical information
Can identify which types of browsers are experiencing issues
Used in requests

Server #

Software information of the ORIGIN server processing the request

Server: Apache/2.2.22(Debian)
server: nginx
Used in responses

Date #

Date and time the message was generated

Date: Tue, 15 Nov 1994 08:12:31 GMT
Used in responses

Special Information #

Host: Requested host information (domain)
Location: Page redirection
Allow: Permitted HTTP methods
Retry-After: Time the user agent should wait before making the next request

Host #

Requested host information (domain)

Used in requests
Required
When a single server needs to handle multiple domains
When multiple domains are applied to a single IP address, a server can handle multiple domains at once via virtual hosts, and multiple actual applications can be running.

GET /hello HTTP/1.1
Host: aaa.com

Location #

Page redirection

If a web browser receives a 3xx response with a Location header, it automatically navigates (redirects) to the Location specified.
Explained in response code 3xx
201 (Created): The Location value is the URI of the resource created by the request
3xx (Redirection): The Location value points to the target resource for automatically redirecting the request

Allow #

Permitted HTTP methods

Must be included in the response for 405 (Method Not Allowed)
Allow: GET HEAD PUT

Retry-After #

Time the user agent should wait before making the next request

503 (Service Unavailable): Can indicate until when the service will be unavailable
Retry-After: Fri, 31 Dec 1999 23:59:59 GMT (date format)
Retry-After: 120 (seconds format)