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
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
Failover modes: hot standby: active-passover failover.
Load balance: active-active failover
Both servers active. Best suited for same site deployments