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Network+ Exam

IPV4 Address types

October 29, 2025

  • #network+

IPV4 Address types

Pulblic - routable uniqeu ip address assigned to each device on the internet that allows it to communciate with other addresses on the network . dotted decimal notatpoon eg 66.51.41.112 must be leashed or purchaed managed by

ICANN globally manages and leases publically roubable ip addresses

NA ARIN, LA LACNIC , AFRIC AFNIC APNIC ASIA, RIPE eurpoe.

Private- private (non-routable) used within a local network thtat allows for the ommunicaton between devices within that network without usina. public ip address.

10

172

192

NAT NETWORK ADDRESS TRANSLATION - method that allows a router to be an agent between a public ip address and a private address so that we don’t need to use so many public ip addresses.

RFCs request for comments formal publication from the intent society and the IETF

RFC 1918

Class A 10.0.0.0 -10.255.255.255

Class B 172.26 - 172.31. ** careful with these on the exam.

Class C 192.168

Loopback 127.0.0.1

apipa range 169.254.0.0. to 169.254.255.255

IPV4 Addressing & Special Ranges

Public IP

  • Routable, globally unique addresses used on the Internet.
  • Must be purchased/leased from ICANN/IANA → delegated to Regional Internet Registries (RIRs):
    • ARIN (North America)
    • LACNIC (Latin America)
    • AFRINIC (Africa)
    • APNIC (Asia Pacific)
    • RIPE NCC (Europe, Middle East, parts of Central Asia)

Private IP (RFC 1918)

  • Non-routable; used inside LANs.
  • Requires NAT to reach the Internet.

Ranges:

  • Class A: 10.0.0.0 – 10.255.255.255 (/8)
  • Class B: 172.16.0.0 – 172.31.255.255 (/12) ⚠️ Exam trick: Only 172.16–31 is private; 172.0–15 and 172.32+ are public!
  • Class C: 192.168.0.0 – 192.168.255.255 (/16)

Other Important Ranges

  • Loopback: 127.0.0.1 (used to test TCP/IP stack).
  • APIPA (Automatic Private IP Addressing): 169.254.0.0 – 169.254.255.255
    • Assigned when DHCP fails.
    • Self-assigns an address, only valid on the local segment.

NAT (Network Address Translation)

  • Allows private IP devices to access public networks by translating private ↔ public addresses.
  • PAT (Port Address Translation): many private devices share one public IP, differentiated by port numbers.

✅ Exam Tips

  • RFC 1918 = private IP ranges.
  • APIPA = 169.254.x.x (DHCP failure fallback).
  • Loopback = 127.0.0.1.
  • NAT is critical for conserving IPV4 addresses.

⚡ Flashcards

  • Q: What organization globally manages public IPs?

    A: ICANN/IANA.

  • Q: Which RFC defines private IP ranges?

    A: RFC 1918.

  • Q: What’s the Class B private IP block?

    A: 172.16.0.0 – 172.31.255.255.

  • Q: What address range does Windows use when DHCP fails?

    A: 169.254.0.0/16 (APIPA).