What is IPv6?

IPv6 replaces IPv4: 128-bit addresses, hexadecimal notation, no NAT requirement, no broadcast (multicast instead). 2001:0db8:abcd:0012:0000:0000:0000:0001 = 2001:db8:abcd:12::1 Structure Network prefix + Interface ID; /64 is the standard subnet — first 64 bits network, last 64 host. SLAAC only works on /64 (classic trap). Address types Global Unicast — 2000::/3, the internet-routable one Link-Local — FE80::/10, […]

Special IPv4 Addresses

Type Range / rule Routable Network address All host bits = 0 (192.168.1.0/24) No — never a host Broadcast All host bits = 1 (192.168.1.255) No — never a host Loopback 127.0.0.0/8 (usually 127.0.0.1) No — router loopbacks make great Router IDs APIPA 169.254.0.0/16 No — Windows self-assigned when DHCP fails; no default gateway Exam […]

Private vs Public IP Addresses

Private addresses are used internally and cannot be routed on the internet; public addresses are globally routable (assigned by ISP/RIR). RFC 1918. Ranges 10.0.0.0/8 172.16.0.0/12 192.168.0.0/16 Motivation: IPv4 exhaustion, internal networks without global routing, isolation. Private space is reused everywhere; NAT translates private ↔ public at the edge. 10.x / 172.16–31.x / 192.168.x → always […]