cisco ccna testing center

cisco ccna testing center.58 Chapter 1 Network Protocols and Network Device Basicsto be manually configured by a human. This method of IP address assignment is commonly used for network devices or servers whose IP addresses are important and always remain the same. For example, the following command can be executed to assign an IP address to the F0/0 interface of a CiscoiOS router.What if there is no DHCP server on the LAN? If you still want the host to obtain an address automatically, you need to enable the DHCP relay or DHCPhelper feature of a Layer 3 device (for example, a router). Once such a feature is enabled, the router will receive DHCP broadcast messages (e.g., DHCPDISCOVERY and DHCPREQUEST messages) from the host (DHCP client) and forward them unicast to the IP address of the DHCP server specified by the DHCP relay-related command, as shown in Figure 1.54. Once the DHCP server replies with the above message, the router forwards it to the host.An example of a DHCP relay is shown in Figure 1.54. As can be seen from the figure, the host sends DHCP DISCOVERY messages in broadcast mode within its own directly connected network segment (10.0.1.0/24). Router R1 has a statement like ip dhcp helper address 10.0.1.1 to provide DHCPhelper functionality within network segment 10.0.1.0/24. Therefore, R1 receives DHCPREQUEST messages, which are then forwarded to the IP address of the DHCP server configured on the local machine. The DHCP server sends a DHCP OFFER message in response to the DHCP DISCOVERY message. The DHCP OFFER message will be delivered directly to the DHCPhelper address set by R1. After receiving this message from the DHCP server, R1 forwards it to the host.The DHCPServer.10.0.5.2Forwarded as unicast to 10.0.5.2 10.0.5.0/24DHCP DISCOVERY messagesSend as broadcast