Download DHCP

DHCP
Dynamic Host Configuration
Protocol
What is DHCP?
It does name resolution (one more?!)
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DNS resolves IP numbers and FQDN
WINS resolves NetBIOS names and IP
numbers
ARP resolves IP numbers and MAC
addresses (outgoing packets)
DHCP resolves IP numbers and MAC
addresses dynamically
The Windows BootP
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BootP is a table of IP numbers and MAC
addresses on a server
DHCP is a dynamic BootP
How does it work?
(1)
IP scope
DHCP discover
DHCP
CLIENT
(0)
MAC address
DHCP offer
IP#, lease time
DHCP
SERVER
(2)
DHCP request
DHCP
CLIENT
DHCP
DATABASE
IP#, MAC address
DHCP ack
MAC address, IP#,
lease time
IP#, lease time
• Scope - a range of IP addresses
• IP lease - the IP# is assigned temporarily
• Reserved IP - servers are assigned fixed IP addresses
Pros
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Pros and Cons
simplifies the task of assigning IP numbers to
each machine in the network
makes easy to add, remove or move a host
can assign defaults: default gateway, domain
name, DNS server, WINS server (if any) .
ability to have fewer IP# than hosts
 Cons
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if DHCP server is down, all hosts are down
hard to keep information on free and used IP #
Multi-DHCP networks
No server coordination
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each subnet can only have one scope
(continuous, but you can exclude some IP
addresses), but
you can create DHCP servers with nonoverlapping scopes to the same subnet
(not MS party line)
Backup and fault tolerance
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DHCP makes an hourly backup of its
database
it can recover itself, but you should do a
backup of its backup if you think
Install and setup
Install
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open network in control panel, select
services
add MS DHCP Server, press OK and close
system will need to reboot, do it
when re-starts DHCP is installed and
started as a service
Setup
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open DHCP Manager and select create
scope
enter the range of IP# and exclusions as
shown
DHCP and IPCONFIG
IPCONFIG/ALL
FQDN, servers (DNS, WINS), node type, etc
 NIC description, MAC address, IP address,
gateway, subnet mask
To handle leases
 IP CONFIG/RENEW [adapter]
 IP CONFIG/RELEASE [adapter]
 if no adapter name is specified, then the IP
leases for all adapters bound to TCP/IP will
be released or renewed.
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