Basic Networking Rules

What is an IP Address?

A logical, software-based address used to identify a device's location on a network.

Can an IP address change?

Yes, it can change dynamically or be set statically depending on the network.

Avionics systems that use IP addresses

Maintenance laptops, test equipment, and Ethernet-based systems (e.g., B787 / A350).

What core question does an IP address answer?

"Where am I on this network right now?"

What is a MAC Address?

A permanent physical hardware identifier assigned to a device by the manufacturer.

Can a MAC address normally be changed?

No, it is permanently burned into the hardware interface or avionics module.

Give an example format of a MAC address

00:1A:2B:3C:4D:5E (or separated by hyphens)

What core question does a MAC address answer?

"What am I (hardware identity)?"

Mailing analogy: What do MAC and IP addresses represent?

MAC address = Serial number of the device; IP address = Street address where it sits.

Difference: How are IP and MAC addresses assigned?

IP is assigned by the network/admin; MAC is assigned by the manufacturer.

Difference: What type of addresses are IP and MAC?

IP is a logical address; MAC is a physical address.

What is the function of a Subnet Mask?

It defines which part of an IP address belongs to the network and which part belongs to the device.

Subnet Mask rule of thumb

Everything left of the mask = network portion; Everything right = device portion.

In IP 192.168.1.10 with mask 255.255.255.0, what is the network portion?

192.168.1

In IP 192.168.1.10 with mask 255.255.255.0, what is the device (host) portion?

.10

Why do modern aircraft networks use subnetting?

To safely separate systems (flight controls, entertainment, diagnostics) and prevent interference.

Where can an avionics technician find a physical hardware MAC address?

Printed on device labels, network module stickers, or LRU documentation.

What Windows command is used on a maintenance laptop to find a MAC address?

ipconfig /all (labeled as Physical Address)

What software system on an aircraft can display a module's MAC address?

Maintenance software or Built-In Test Equipment (BITE) systems.

Mental Model: What is the analogy for a Subnet Mask?

The rules that dictate which houses are located on the same street.

Practice 1: What is a MAC address?

A unique hardware identifier assigned to a network device.

Practice 2: What is an IP address used for?

To identify a device’s location on a network for communication.

Practice 3: What does a subnet mask do?

It separates the network portion of an IP address from the host portion.

Practice 4: Which address is permanent: IP or MAC?

MAC address.

Practice 5: Which address changes depending on the network you connect to?

IP address.

Summary: What are the two-word associations for IP and MAC?

IP = network location; MAC = hardware identity.