Concept Guide
Figure 34. DHCP packet Format
The following table lists common DHCP options.
Option Number and Description
Subnet Mask Option 1
Species the client’s subnet mask.
Router Option 3
Species the router IP addresses that may serve as the client’s default gateway.
Domain Name
Server
Option 6
Species the domain name servers (DNSs) that are available to the client.
Domain Name Option 15
Species the domain name that clients should use when resolving hostnames via DNS.
IP Address Lease
Time
Option 51
Species the amount of time that the client is allowed to use an assigned IP address.
DHCP Message
Type
Option 53
• 1: DHCPDISCOVER
• 2: DHCPOFFER
• 3: DHCPREQUEST
• 4: DHCPDECLINE
• 5: DHCPACK
• 6: DHCPNACK
• 7: DHCPRELEASE
• 8: DHCPINFORM
Parameter Request
List
Option 55
Clients use this option to tell the server which parameters it requires. It is a series of octets where each octet is
DHCP option code.
Renewal Time Option 58
Species the amount of time after the IP address is granted that the client attempts to renew its lease with the
original server.
Dynamic Host Conguration Protocol (DHCP) 321