CompTIA A+ 220-1201 (2.6 - Assigning IP Addresses)

Networking with IPv4

• IP Address, e.g., 192.168.1.165

- Every device needs a unique IP address

• Subnet mask, e.g., 255.255.255.0

- Used by the local device to determine

what subnet it's on

- The subnet mask isn't (usually) transmitted

across the network

- You'll ask for the subnet mask all the time

- What's the subnet mask of this network?

• Default gateway, e.g., 192.168.1.1

- The router that allows you to communicate

outside of your local subnet

- The default gateway must be an IP address

on the local subnet

Static IP addressing

• An IP address that doesn't change

- Without a manual configuration change

• Manually configure the IP address

- Type it from the keyboard on each device

• Can be difficult to manage

- If the address changes, you must visit the device

- This obviously does not scale

• Try to avoid using manual IP addressing

- There are better ways to assign addresses

- DHCP reservations

Turning dynamic into static

• DHCP assigns an IP address from the first available from a large pool of addresses

- Your IP address will occasionally change

• You may not want your IP address to change

- Server, printer, or personal preference

• Disable DHCP on the device

- Configure the IP address information manually

- Requires additional administration

• Better: Configure an IP reservation on the DHCP server

- Associate a specific MAC address with an IP address

Automatic Private IP Addressing (APIPA)

• A link-local address - No forwarding by routers

• APIPA uses 169.254.0.0 through 169.254.255.255

- First and last 256 addresses are reserved

- Functional block of 169.254.1.0 through 169.254.254.255

• Randomly assigned in this block

- Uses ARP to confirm the address isn't currently in use