Transcript Dynamic Host Configuration Protocol

Dynamic Host Configuration
Protocol and IP Address Assignment
CIS 238
Oakton Community College
Methods for Assigning IP
Addresses
• Static assignment
– Manually assign an IP address to a host
• Dynamic assignment
– Configure a host to obtain an IP address
automatically using DHCP (Dynamic Host
Configuration Protocol)
DHCP Lease Process
DHCP Operation
• Common problem on networks attempting to
implement DHCP: routers do not pass broadcasts
• Solutions
– Configure a router to pass DHCP traffic (smart relay)
– Place second DHCP server on same segment as the client
– Use a DHCP relay agent to act as a proxy for a DHCP server
DHCP Definition
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Create DHCP Scope
Define dynamic pool
Define lease reservation(s)
Define gateway
Define scope options – DNS, Active Directory
DHCP Scope Options
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Name and Description
IP Address range
Subnet mask
Add Exclusions
Lease duration
Configure DHCP Options
Local specific options (Windows, VoIP)
- Options that apply to all clients in one scope only
-Vendor-defined option classes
- User-defined option classes
- Reserved client options
Integrating DHCP and DNS
• You can configure DHCP to create Dynamic
DNS entries for clients that do not support
DDNS
– Helps with support of legacy, non-DDNS aware
clients
• Windows clients can register their own A
records but they still rely on the DHCP server
to create reverse lookup records
Troubleshooting DHCP
• A scope that has run out of addresses
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Decrease length of lease for the scope
Increase range of addresses in the scope
Renumber entire scope with new, larger range of addresses
Remove some clients from overcrowded network segment
• An improperly configured network
– Place a DHCP server on each subnet
– Implement DHCP relay agents on subnets without DHCP servers
• DHCP Service down or missing Relay Agent
• ipconfig /all or ifconfig –a
• Windows: 169.254.xx.xx addresses on an interface or showing
up on a network segment (no local DHCP server or relay).