DHCP

• Dynamic Host Configuration Protocol is a client/server protocol that automatically provides a host with its IP address and other related configuration information such as the subnet mask and default gateway.
• DHCP Relay Agent's forward DHCP messages, eliminating the need for a DHCP server on every subnet
• DHCP requests are Broadcast messages

DHCP Operations

DORA: DHCP Operations Order

1. Discover: DHCP Discover (Client, Broadcast)
2. Offer: DHCP Offer (Server, Unicast/Broadcast)
3. Request: DHCP Request (Client, Broadcast)
4. Ack: DHCP Ack (Server, Unicast/Broadcast)

DHCP Server messages

1. OFFER
   1. Initial response to a client request
2. ACK
   1. Provisioning of IP address and DHCP information
3. NAK
   1. Decline's a user's request for provisioning
      1. Opposite of an ACK

DHCP Client Messages

1. DISCOVER
   1. Initial packet searching for a DHCP server
2. REQUEST
   1. IP address/DHCP information provisioning request
3. RELEASE
   1. Release of leased IP address
4. DECLINE
   1. Decline offered IP address by a server

DHCP Commands

• Create a DHCP pool
  • Config# ip dhcp pool <Pool Name>
• Lease shows detailed information related to the IP lease itself, like renewal time, client hostname, etc.
  • # sho dhcp lease
• Binding shows summary device-specific information (i.e., MAC address, expiration, etc.)
  • # sho dhcp binding

Metadata

OSI or TCP/IP Layer

CCNA Exam Topic

#extop-4-3 #extop-4-6

Contributors

Sources