Dell PowerSwitch S4112F-ON EMC SmartFabric OS10 User Guide Release 10.5.0 - Page 200

DHCP server DHCP client Relay agent Network device offering configuration parameters to the client. Network device requesting configuration parameters from the server. Intermediary network device that passes DHCP messages between the client and the server when the server is not on the same subnet as the host. Packet format and options The DHCP server listens on port 67 and transmits to port 68. The DHCP client listens on port 68 and transmits to port 67. In the DHCP packet format, configuration parameters are options in the DHCP packet in type, length, value (TLV) format. To limit the number of parameters that servers provide, hosts enter the parameters that they require and the server sends only those parameters. DHCP uses the User Datagram Protocol (UDP) as its transport protocol. The following options are commonly used in DHCP packets. DHCP Option Description Subnet mask Router Domain name server Domain name IP address lease time DHCP message type 1 - Subnet mask of the client 3 - Router IP addresses that serve as the default gateway for the client 6 - Domain name servers (DNS) that are available to the client 15 - Domain name that clients use to resolve hostnames via DNS 51 - Amount of time that the client uses an assigned IP address 53: • 1 - DHCPDISCOVER • 2 - DHCPOFFER • 3 - DHCPREQUEST • 4 - DHCPDECLINE • 5 - DHCPACK • 6 - DHCPNACK • 7 - DHCPRELEASE • 8 - DHCPINFORM 200 System management