Chapter 7: TCP/IP Basics pg 216 - End

Dynamic IP Addressing 
- Dynamic Host Configuration Protocol (DCHP)
      -> automatically assigns an IP whenever a computer connects to the network

How DHCP Works( Uses ports 67 and 68)
- DHCP Client
- automatically sens out a special DHCP discover packet using the broadcast address
- discover message searches for DHCP servers
- one system on the LAN must be running DHCP server software
- designed to respond to DHCP discover requests
- DHCP server is configured to pass out IP addresses from an IP range (scope)
- DHCP servers can be set up to reserve addresses for specific machines (reservations)
- DHCP client sends out a DHCP request
- DHCP server then sends  DHCP acknowledge and lists the MAC address and IP information
- DHCP lease: the acceptance from the DHCP client of the DHCP server's data
         -> set for a fixed amount of time (5-8 days)
         -> near the end of the lease time, the DHCP client simply makes another DHCP Discover message
- DHCP server looks at the MAC address information and gives the DHCP client the same IP info

Living with DHCP
- biggest issue: a DHCP client tries to get a DHCP address and fails
        -> indicated by the operating system posting some form of error and the DHCP client has a strange  IP address
- Automatic Private IP Addressing (APIPA) : generates the "special" IP address
        -> all DHCP servers generate an APIPA address automatically if they do not recieve a response to  a DHCP Discover message
        -> DHCP client only generates the last two octets of an APIPA address
        -> APIPA cannot issue a default gateway which prevents internet access
        -> systems that use static IP addressing can never have DHCP problems

What to Remeber:

1. An IPv4 address consists of 32 bits.
2. The network ID is the first three octets when using the specified subnet
3. A subnet is all 1s followed by 0s