A distributed system of linked hypertext resources identified by URLs and accessed using HTTP

What is the structure of an HTTP message?

Start line, header lines, blank line, optional body

Body, then headers, then start line

Why is the Host header important in HTTP/1.1?

It is required and supports virtual hosting

Which describes persistent connections with pipelining?

Connection stays open and many requests are sent without waiting, about 1 RTT total

New TCP connection per object, 2 RTT each

Connection:close after each response

2072 Magh · 2+8 marks

WWW; HTTP header and connection types

Short answer

The World Wide Web is a distributed hypertext system using URLs and HTTP. HTTP headers are Name:value metadata lines. Connection types are non-persistent (Connection: close, one object per TCP) and persistent (Connection: keep-alive, multiple objects on one TCP, with optional pipelining).

What is WWW? Define HTTP header with its connection type.

What is WWW?

The World Wide Web (WWW) is a distributed information system of linked hypertext documents and other resources, each identified by a URL and accessed over the Internet using HTTP. Documents are written in HTML, displayed by a browser (client) and stored on web servers. It was proposed by Tim Berners-Lee at CERN in 1989. The web is one service on the Internet; e-mail and FTP are others.

HTTP header

HTTP messages consist of a start line, header lines, a blank line, and an optional body. Headers are Name: value pairs giving extra information about the message, client, server or body.

Request message

GET /index.html HTTP/1.1
Host: www.example.com
User-Agent: Mozilla/5.0
Accept: text/html
Accept-Language: en
Connection: keep-alive
If-Modified-Since: Wed, 9 Sep 2020 09:23:24

Response message

HTTP/1.1 200 OK
Date: Thu, 8 Oct 2026 10:00:00 GMT
Server: Apache/2.4
Last-Modified: Wed, 9 Sep 2020 09:23:24
Content-Length: 6821
Content-Type: text/html
Connection: keep-alive

Common headers: Host (required in HTTP/1.1, supports virtual hosting), User-Agent, Accept, Cookie / Set-Cookie, Content-Type, Content-Length, Cache-Control, Expires, Last-Modified, Location.

Connection types (the Connection header)

Non-persistent connection (HTTP/1.0). Each object needs a new TCP connection, which the server closes after sending one object (Connection: close). Costs 2 RTT per object plus server overhead.
Persistent connection (HTTP/1.1 default, Connection: keep-alive). The connection stays open for further requests to the same server.
- Without pipelining: next request after the previous response arrives (about 1 RTT per object).
- With pipelining: the client sends many requests without waiting for replies (about 1 RTT total for all objects).

The connection stays open until a timeout, or until either side sends Connection: close.

✓ Answer checked by Claude Opus 5.5 (high effort)

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