MAC Addresses & IP Addresses
1. What is an Address in Networking?
data can be sent to the correct destination — just like a house needs a
postal address to receive letters.
2. MAC Address — Media Access Control Address
What is a MAC Address?
a Network Interface Card (NIC) by its manufacturer.
MAC Address = A unique 48-bit identifier permanently burned into
a NIC that identifies a device on a local network (LAN).
Format of a MAC Address
Example: A3 : B2 : C1 : D4 : E5 : F6
────────────── ──────────────
First 3 pairs Last 3 pairs
Manufacturer ID Device ID(e.g. Intel, Cisco, Apple).
How MAC Addresses are Used
between devices on the same network.
to a physical port.
and forwards it to the correct device only.
MAC Address Filtering
allow devices with specific MAC addresses to connect.
| ✅ Advantage | ❌ Disadvantage |
|---|---|
| Prevents unauthorised devices connecting | MAC addresses can be spoofed (faked) |
| Easy to implement | Time-consuming to manage on large networks |
3. IP Address — Internet Protocol Address
What is an IP Address?
so it can be identified and communicate across local and wide area networks,
including the internet.
IP Address = A numerical label assigned to every device on a network
used to identify and locate it for communication purposes.
IPv4 — Internet Protocol Version 4
Example: 192 . 168 . 1 . 1
───────────────────────────
32 bits total (4 × 8 bits)this led to the development of IPv6.
IPv6 — Internet Protocol Version 6
(3.4 × 10³⁸) — essentially unlimited.
IPv4 vs IPv6 Comparison
| Feature | IPv4 | IPv6 |
|---|---|---|
| Bit length | 32 bits | 128 bits |
| Format | Decimal, dotted (e.g. 192.168.1.1) | Hexadecimal, colon-separated |
| Total addresses | ~4.3 billion | ~340 undecillion |
| Address exhaustion | ✅ Running out | ❌ Not an issue |
| Example | 192.168.1.1 | 2001:0db8:85a3::8a2e:0370:7334 |
Static vs Dynamic IP Addresses
| Type | Description | Assigned by | Changes? |
|---|---|---|---|
| Static IP | Permanently fixed address | Manually by admin | ❌ Never |
| Dynamic IP | Temporary address assigned each session | Router via DHCP | ✅ Can change |
that automatically assigns IP addresses to devices when they join a network.
consistent, known address.
as addresses are reused.
4. How MAC and IP Addresses Work Together
different levels of the network:
Analogy
| Address Type | Real-World Equivalent |
|---|---|
| IP Address | The postal address of a building (used to navigate to the right location) |
| MAC Address | The name on the door of a specific flat inside that building |
5. ARP — Address Resolution Protocol
its MAC address to deliver data on the local network, it uses ARP.
ARP = A protocol that maps a known IP address to its corresponding
MAC address on a local network.
6. Public vs Private IP Addresses
| Type | Description | Example Range |
|---|---|---|
| Private IP | Used within a local network (LAN) — not routable on the internet | 192.168.x.x / 10.x.x.x |
| Public IP | Assigned by the ISP — used to identify the network on the internet | Varies — assigned by ISP |
to the single public IP.
7. Full Comparison — MAC Address vs IP Address
| Feature | MAC Address | IP Address |
|---|---|---|
| Full name | Media Access Control Address | Internet Protocol Address |
| Purpose | Identify device on local network | Identify device across networks |
| Assigned by | Manufacturer | Network / Router (DHCP) |
| Permanent? | ✅ Yes — fixed at manufacture | ❌ No — can change |
| Length | 48 bits | 32 bits (IPv4) / 128 bits (IPv6) |
| Format | Hexadecimal pairs (AA:BB:CC:DD:EE:FF) | Decimal dotted (192.168.1.1) |
| Scope | Local network (LAN) only | Local and wide area (WAN/Internet) |
| Layer | Data Link Layer | Network Layer |
| Used by | Switch | Router |
| Can be changed? | ❌ No (can be spoofed but not truly changed) | ✅ Yes |
| Unique globally? | ✅ Yes | ✅ Public IPs yes / Private IPs no |
8. Summary — How Addressing Works End to End
9. Key Vocabulary
| Term | Definition |
|---|---|
| MAC Address | A unique 48-bit permanent hardware address assigned to a NIC |
| IP Address | A logical address assigned to a device for network communication |
| IPv4 | 32-bit IP address format — approximately 4.3 billion addresses |
| IPv6 | 128-bit IP address format — created due to IPv4 exhaustion |
| Static IP | A fixed, manually assigned IP address that never changes |
| Dynamic IP | An IP address assigned automatically by DHCP that can change |
| DHCP | Dynamic Host Configuration Protocol — automatically assigns IP addresses |
| ARP | Address Resolution Protocol — maps an IP address to a MAC address |
| OUI | Organisationally Unique Identifier — first 3 pairs of a MAC address identifying the manufacturer |
| NAT | Network Address Translation — maps private IPs to a public IP |
| Private IP | An IP address used within a local network, not routable on the internet |
| Public IP | An IP address assigned by an ISP, used to identify a network on the internet |
| Switch | A network device that uses MAC addresses to forward data |
| Router | A network device that uses IP addresses to route data between networks |
10. Exam Tips ✅
MAC is permanent and physical; IP is logical and can change.
this distinction is very frequently tested.
— know both formats.
and that it is 128 bits (vs IPv4's 32 bits).
for home networks.
and an IP address?"
→ MAC is needed to deliver data within a local network;
IP is needed to route data across different networks and the internet.
always be found at the same address.
directly accessible from the internet.
Modified at 2026-04-03 10:05:10