Dynamic host config protocol.  

Client asks for an ip address via a broadcast address(not routable so has to be on same subnet) if a dhcp server is on the dhcp it passes out an address. If no dhcp server on subnet, a dhcp relay will allow send it to another DHCP server.  

4 phases: dhcp disvocer message, server looks in scope and sends a dhcp offer, Dhcp request message si sent back (acceptance fo ip address) DHcpAck. Lease is 8 days for a wired client. After 50 and 75% of lease is expired, client will send DHCP renew and server will send DHCPack back.  

Scopes: pool of ip address. Usually likned to a specific subnet.  


Reservations: assigns mac addresses to ip address 


Setting up scopes: can include the whole subnet and add exclusion (ips that are static) 

Options allw us to push out dns, default gateway 


Madcap: used to assign multicast addresses. Multicast is for streaming audo and video.  


128 bit address 

Allows auto config of clients. Routers do more work 

Local router have router advertisemnts so deault gateways are obsolute 

DuiD, IAD 

OPtianing ipv6 address: static, SLaac, dhcpv6 

SLAAC: host generated address. Router advertisemnts utilized. Dhcpv6 can be used only for config info 

Stateful config: server provided address and/or config info. Used for nin-link local addressing. Utilizes dhcpv6 

Router advert flags: m flag and o flag 

Dhcp: uses stores scopes and leases. Joint engine database, uses transaction logs 

DNS dynamic updates.  

Dns name protection” when a client gets an ip address through dhcp, it sends a message to dns to make a dhcid rr associating ip address with client name(A record). Wont prevent getting an ip address for another client but from grabbing the same name 

Migrating a dhcp server 

Preferred method: dhcp database and dhcp server settings 

PLaaning for migration: verify prerequisites, backups, prepare servers, backout plan 

Dhcp failover 

Failover modes: hot standby: active-passover failover. 

Load balance: active-active failover 

Both servers active. Best suited for same site deployments