关于DHCP的简单理解

1、DHCP这个在网络中的高频词是什么？（what）

DHCP:动态主机配置协议（Dynamic Host Configuration Protocol）,从名称中我们可以看出，这是一个协议，并且该协议的工作任务是主机配置 ，方式是动态的！，这就是我们一开始的印象 ！

接下来，我们在进一步探究：
动态，主机 ，配置，协议

Dynamic – Automatically
Host – Any computer that is connected to the network
Configuration – To configure a host means to provide network information(ip address,subnet mask,Gateway address) to a host
Protocol – Set of rules

2、DHCP 是 怎么工作的？（how）

在探究DHCP是怎么工作之前，我们需要看一看DHCP是由什么的?

Components of DHCP:
DHCP server: A networked device running the DCHP service that holds IP addresses and related configuration information. This is most typically a server or a router but could be anything that acts as a host, such as an SD-WAN appliance.
DHCP client: The endpoint that receives configuration information from a DHCP server. This can be a computer, mobile device, IoT endpoint or anything else that requires connectivity to the network. Most are configured to receive DHCP information by default.
IP address pool: The range of addresses that are available to DHCP clients. Addresses are typically handed out sequentially from lowest to highest.
Subnet: IP networks can be partitioned(分割) into segments(部分、段) known as subnets. Subnets help keep networks manageable.
Lease: The length of time for which a DHCP client holds the IP address information. When a lease(租期) expires(到期), the client must renew it.
DHCP relay: A router or host that listens for client messages being broadcast on that network and then forwards them to a configured server. The server then sends responses back to the relay agent(中继代理) that passes them along to the client. This can be used to centralize(中心化) DHCP servers instead of having a server on each subnet.

了解到dhcp的组成之后我们以图示的方式展示dhcp的工作过程：


dhcp服务器设置

下图中除了客户端的请求与服务器端的响应之外，还展示了dhcp的状态转换：initializing(初始化)、selecting(选择)、requesting(请求)、bound(绑定)、[renewing(续租)、rebinding(重新绑定)]，具体细节自己查询资料。

3、我们作为是怎么成为dhcp client？在哪配置的？（where）

关于dhcp的配置如下图:

上面是我电脑上的关于以太网的network information，我们也可以 观察到，默认网关和DHCP服务器是同一个ip地址