同一个局域网内存在两台DHCP服务器

也就是说你获取的是另外一个DHCP服务器分配的地址，那你可以进入CMD，使用IPCONFIG /ALL 查看DHCP SERVER，会告诉你DHCP服务器的IP地址是多少，知道了地址你用MAC地址扫描器就能知道这个IP地址所对应的计算机名是什么？如果你知道了计算机名还不知道是哪个机器，那么你就得一台一台的找了。

注：网络中有没有路由器相关的设备，因为路由器或防火墙的DHCP默认时是开启的。

0(∩＿∩)O

（1）简单实现DHCP多作用域

对于多作用域的配置，必须保证DHCP服务器能够侦听所有子网客户机的请求信息，下面将讲解配置多作用域的基本方法，为DHCP添加多个网卡连接每个子网，并发布多个作用域的声明。

注意：划分子网时，如果选择直接配置多作用域实现动态IP分配的任务，则必须要为DHCP服务器添加多块网卡，并配置多个IP地址，否则DHCP服务器只能分配与其现有网卡IP地址对应网段的作用域。

采用双网卡实现两个作用域

1）网卡配置IP地址

DHCP服务器有多块网卡时，需要使用ifconfig命令为每块网卡配置独立的IP地址，但要注意，IP地址配置的网段要与DHCP服务器发布的作用域对应哈~

ifconfig eth0 19216821 netmask 2552552550

ifconfig eth1 19216831 netmask 2552552550

2）编辑dhcpdconf主配置文件

当DHCP服务器网络环境搭建完毕后，可以编辑dhcpdconf主配置文件完成多作用域的设置。

ddns-update-style none;

ignore client-updates;

subnet 19216820 netmask 2552552550 {

# --- default gateway

option routers 19216821;

option subnet-mask 2552552550;

option nis-domain "domainorg";

option domain-name "domainorg";

option domain-name-servers 19216822;

option time-offset -18000; # Eastern Standard Time

# option ntp-servers 19216811;

# option netbios-name-servers 19216811;

# --- Selects point-to-point node (default is hybrid) Don't change this unless

# -- you understand Netbios very well

# option netbios-node-type 2;

range dynamic-bootp 192168250 1921682250;

default-lease-time 21600;

max-lease-time 43200;

# we want the nameserver to appear at a fixed address

host ns {

next-server marvinredhatcom;

hardware ethernet 12:34:56:78:AB:CD;

fixed-address 20717542254;

}

}

subnet 19216830 netmask 2552552550 {

# --- default gateway

option routers 19216831;

option subnet-mask 2552552550;

option nis-domain "domainorg";

option domain-name "domainorg";

option domain-name-servers 19216822;

option time-offset -18000; # Eastern Standard Time

# option ntp-servers 19216811;

# option netbios-name-servers 19216811;

# --- Selects point-to-point node (default is hybrid) Don't change this unless

# -- you understand Netbios very well

# option netbios-node-type 2;

range dynamic-bootp 192168350 1921683250;

default-lease-time 21600;

max-lease-time 43200;

max-lease-time 43200;

}

保存退出。

3）测试验证

重启DHCP服务后检查系统日志，检测配置是否成功，使用tail命令动态显示日志信息。

tail -F /etc/log/messages

经过设置，对于DHCP服务器将通过eth0和eth1两块网卡侦听客户机的请求，并发送相应的回应。

Jan 19 16:02:51 rhel5 dhcpd: DHCPDISCOVER from 00:19:21:bd:a3:da via eth1

Jan 19 16:02:51 rhel5 dhcpd: DHCPDISCOVER from 00:19:21:bd:a3:da via eth0

Jan 19 16:02:52 rhel5 dhcpd: DHCPOFFER 1921683250 to 00:19:21:bd:a3:da (mis) via eth1

Jan 19 16:02:52 rhel5 dhcpd: DHCPOFFER 1921682250 to 00:19:21:bd:a3:da (mis) via eth0

Jan 19 16:02:52 rhel5 dhcpd: DHCPREQUEST for 1921683250 (19216831) from 00:19:21:bd:a3:da (mis) via eth1

Jan 19 16:02:52 rhel5 dhcpd: DHCPACK 1921683250 to 00:19:21:bd:a3:da (mis) via eth1

Jan 19 16:02:52 rhel5 dhcpd: DHCPREQUEST for 1921683250 (19216831) from 00:19:21:bd:a3:da (mis) via eth0: ignored (not authoritative)

Jan 19 16:02:53 rhel5 dhcpd: DHCPDISCOVER from 00:19:21:bd:a3:da (mis) via eth1

Jan 19 16:02:53 rhel5 dhcpd: DHCPOFFER 1921683250 to 00:19:21:bd:a3:da (mis) via eth1

Jan 19 16:02:53 rhel5 dhcpd: DHCPDISCOVER from 00:19:21:bd:a3:da (mis) via eth0

Jan 19 16:02:53 rhel5 dhcpd: DHCPOFFER 1921682250 to 00:19:21:bd:a3:da (mis) via eth0

Jan 19 16:02:53 rhel5 dhcpd: DHCPREQUEST for 1921683250 (19216831) from 00:19:21:bd:a3:da (mis) via eth1

Jan 19 16:02:53 rhel5 dhcpd: DHCPACK 1921683250 to 00:19:21:bd:a3:da (mis) via eth1

Jan 19 16:02:53 rhel5 dhcpd: DHCPREQUEST for 1921683250 (19216831) from 00:19:21:bd:a3:da (mis) via eth0: ignored (not authoritative)

Jan 19 16:02:54 rhel5 dhcpd: DHCPDISCOVER from 00:19:21:bd:a3:da (mis) via eth1

Jan 19 16:02:54 rhel5 dhcpd: DHCPOFFER 1921683250 to 00:19:21:bd:a3:da (mis) via eth1

Jan 19 16:02:54 rhel5 dhcpd: DHCPDISCOVER from 00:19:21:bd:a3:da (mis) via eth0

Jan 19 16:02:54 rhel5 dhcpd: DHCPOFFER 1921682250 to 00:19:21:bd:a3:da (mis) via eth0

Jan 19 16:02:54 rhel5 dhcpd: DHCPREQUEST for 1921683250 (19216831) from 00:19:21:bd:a3:da (mis) via eth1

Jan 19 16:02:54 rhel5 dhcpd: DHCPACK 1921683250 to 00:19:21:bd:a3:da (mis) via eth1

Jan 19 16:02:54 rhel5 dhcpd: DHCPREQUEST for 1921683250 (19216831) from 00:19:21:bd:a3:da (mis) via eth0: ignored (not authoritative)

Jan 19 16:02:55 rhel5 dhcpd: DHCPDISCOVER from 00:19:21:bd:a3:da (mis) via eth1

Jan 19 16:02:55 rhel5 dhcpd: DHCPOFFER 1921683250 to 00:19:21:bd:a3:da (mis) via eth1

Jan 19 16:02:55 rhel5 dhcpd: DHCPDISCOVER from 00:19:21:bd:a3:da (mis) via eth0

Jan 19 16:02:55 rhel5 dhcpd: DHCPOFFER 1921682250 to 00:19:21:bd:a3:da (mis) via eth0

Jan 19 16:02:55 rhel5 dhcpd: DHCPREQUEST for 1921683250 (19216831) from 00:19:21:bd:a3:da (mis) via eth1

Jan 19 16:02:55 rhel5 dhcpd: DHCPACK 1921683250 to 00:19:21:bd:a3:da (mis) via eth1

Jan 19 16:02:55 rhel5 dhcpd: DHCPREQUEST for 1921683250 (19216831) from 00:19:21:bd:a3:da (mis) via eth0: ignored (not authoritative)