01 · Configure Your Network
02 · Live Inspector
03 · Key Concepts
Network Bits
Network bits identify which subnet a device belongs to. Every device on the same subnet shares these bits. Think of them as the street name.
Host Bits
Host bits identify the individual device within a subnet. Network address sets all to 0. Broadcast sets all to 1. Everything between is usable.
Borrowing Bits
Move the slider right by 1 and you borrow one host bit. This doubles your subnets but halves your hosts. Every bit is a trade-off.
Why /24 Everywhere?
A /24 gives 254 usable hosts - enough for any home or small office. It's one full octet for hosts. Your router is almost certainly 192.168.x.0/24 right now.
01 · Configure Your IPv6 Network
IPv6 is read as eight 16-bit hextets. The prefix boundary can split a hextet at an exact bit.
Canonical text uses lowercase, removes leading zeros, and compresses one longest zero run.
Routing accepts any prefix length. /64 is the normal SLAAC subnet boundary.
Type and scope come from defined leading bit patterns.
02 · IPv6 Inspector
How to Read an IPv6 Address
An IPv6 address is 128 bits written as 8 groups of 4 hex digits, separated by colons. Each group is called a hextet (16 bits).
2001:0db8:85a3:0000:0000:8a2e:0370:7334
Two shorthand rules make them shorter:
- Drop leading zeros in each hextet:
0db8becomesdb8,0370becomes370 - Replace one run of all-zero hextets with
::(only once per address)::0000:0000:becomes::
So the address above compresses to: 2001:db8:85a3::8a2e:370:7334
Prefix vs Interface ID
In IPv6, there is no subnet mask in dotted-decimal form. Instead, you just use CIDR prefix length (the /64 part).
- Prefix (network portion): identifies which network the device belongs to. Drag the slider to change it.
- Interface ID (host portion): identifies the specific device on that network. In a /64, this is the last 64 bits.
Unlike IPv4, there is no broadcast address in IPv6. Instead, IPv6 uses multicast (ff02::1 for all nodes). Every address in the range is usable.
Common IPv6 Prefix Lengths
/128- a single host (loopback::1, or a specific device route)/64- the standard subnet. SLAAC (auto-config) requires this. Almost every LAN uses /64./48- typical allocation from an ISP to a customer site. Gives you 65,536 /64 subnets./32- allocation from a RIR to an ISP. 4 billion subnets available to hand out./10- link-local scope (fe80::/10). Auto-assigned on every interface, never routed./7- unique local addresses (fc00::/7, practicallyfd00::/8). The IPv6 equivalent of RFC 1918 private space.
Key Differences from IPv4
- No broadcast - IPv6 uses multicast and anycast instead. No more broadcast storms.
- End-to-end addressing - IPv6 removes address scarcity as the reason for NAT. Firewalls and routing policy still control reachability.
- Auto-configuration - SLAAC combines an advertised prefix with an interface identifier. Modern systems commonly use stable opaque or temporary identifiers instead of exposing a MAC address.
- Simpler headers - fixed 40-byte header, no checksum (handled by link layer), no fragmentation by routers.
- No IPv4-style -2 rule - IPv6 has no broadcast address. Special and anycast uses still matter, including the all-zero Subnet-Router anycast identifier on router subnets.
Practice Mode
Test what you know. The bits don't lie.
Question
10.4.12.200/22
What is the network address?