The internet, the web and IP addressing
| English | Chinese | Pinyin |
|---|---|---|
| internet | 互联网 | hù lián wǎng |
| IP address | IP地址 | IP dì zhǐ |
| World Wide Web | 万维网 | wàn wéi wǎng |
| subnet | 子网 | zi wǎng |
| subnet mask | 子网掩码 | zi wǎng yǎn mǎ |
| routable | 可路由的 | kě lù yóu de |
| ISP | 互联网服务提供商 | hù lián wǎng fú wù tí gōng shāng |
The internet 互联网 and the web
- People say "internet" and "web" as if they mean the same thing — they don't.
- The internet is the global infrastructure; the web is just one service on it.
- And every device on it needs an address: an IP address IP地址.
Network route lab
Follow data from a device through network hardware and protocols.
Internet vs the World Wide Web 万维网
- The internet is a global network of networks using a common protocol suite (TCP/IP).
- The World Wide Web (WWW) is a service that runs over it: hyperlinked documents (URLs) viewed in browsers via HTTP/HTTPS.
- Email and file transfer are other internet services that are not part of the WWW.
A router connects a LAN to the internet or another network
What is the relationship between the internet and the World Wide Web?
The internet is the global network; the WWW is one service on it (hyperlinked documents). Email and file transfer are other internet services.
IP addresses
- An IP address uniquely identifies a device on a network.
- IPv4 — 32-bit, four denary numbers 0–255 (
192.168.1.10); only about $4.3 \times 10^9$ addresses (now exhausted). - IPv6 — 128-bit, eight groups of four hex digits; about $3.4 \times 10^{38}$ addresses — vastly more.
The Web is one service running on top of the Internet
How many bits are in an IPv4 address?
IPv4 is 32-bit (four numbers 0–255). IPv6 is 128-bit.
The main reason IPv6 was introduced is that:
IPv4's ~4.3 billion addresses are exhausted; IPv6's 128 bits give about $3.4 \times 10^{38}$ addresses.
Match each term to what it is.
The internet is the infrastructure; the web is one service on it. IPv6 has far more addresses than IPv4.
Subnetting
- A network can be split into subnets 子网. The IP address divides into a network part and a host part.
- A subnet mask 子网掩码 (e.g.
255.255.255.0) marks which bits are the network part (here the first 24). - Subnetting improves management, cuts broadcast traffic, and improves security.
Subnetting splits one network into smaller subnets — here one netID per department.
A subnet mask is used to:
The mask (e.g. 255.255.255.0) marks the network bits, splitting the address into network and host portions.
Public/private and static/dynamic
- Private addresses are used inside a LAN and are not routable 可路由的 on the internet (e.g.
192.168.x.x); public addresses are globally unique, assigned by an ISP 互联网服务提供商. - Devices behind NAT with private addresses aren't directly reachable from outside — some protection.
- Static IPs are fixed (for servers that must be found at a known address); dynamic IPs are handed out by DHCP and may change (easier for client devices).
A static IP address is most suitable for:
Servers need a fixed address so clients can always reach them. Client devices usually get dynamic addresses from DHCP.
A private IP address (e.g. 192.168.1.5):
Private addresses work only inside the LAN and are not routed on the internet; NAT lets them share a public address.
You've got it
- the internet = network of networks (TCP/IP); the WWW = one service (web pages) on it
- IPv4 = 32-bit (≈4.3 billion, exhausted); IPv6 = 128-bit (vastly more)
- a subnet mask splits an IP into network + host parts
- private (LAN, not routable) vs public (ISP); static (servers) vs dynamic (DHCP)