Every PingLabz lab, cheat-sheet PDF, and reference article uses the same IP scheme. This Page is the source of truth. Bookmark it. When you spin up the next lab and the addresses look strangely familiar, this is why - we deliberately reuse the same blocks across the entire library so labs reinforce each other instead of asking you to relearn a new addressing scheme every time.
The scheme is built from RFC 1918 private space (10.0.0.0/8 primarily), RFC 5737 documentation space (192.0.2.0/24 for any inter-AS or public-internet simulation), and consistent role conventions across the second octet so the address tells you what it is at a glance.
The full scheme
10.255.0.1, 10.255.0.2, 10.255.0.3, ...10.30.30.0/30, 10.30.31.0/30, ...10.20.0.0/2410.20.1.0/2410.40.0.0/16172.20.0.0/16, e.g. 172.20.10.0/24192.0.2.0/30192.0.2.1Protocol identifiers
VLAN scheme
Credentials
Every router and switch in PingLabz labs ships with the same baseline credentials. This is not a production pattern - in production you would use a unique secret per device and centralized AAA. For labs the priority is fast access, not credential rotation.
How to read the second octet
You can usually tell what a PingLabz lab address is for at a glance:
- 10.20.x.x - host LAN segments
- 10.30.x.x - point-to-point transit links
- 10.40.x.x - inter-area / summarized networks
- 10.255.0.x - loopbacks (router-IDs, management)
- 172.20.x.x - external / redistributed routes
- 192.0.2.x - inter-AS or public-internet simulation
The CCNA Base Topology address layout
The reusable five-node base topology that powers most labs in the CCNA Labs library uses this scheme out of the box:
10.255.0.1/3210.255.0.2/3210.255.0.3/3210.20.0.0/2410.30.30.0/3010.20.1.0/24Frequently asked questions
Why these blocks specifically?
RFC 1918 (private 10/8) gives us enough address space to never run out. The second-octet conventions (20/30/40) are arbitrary but consistent. RFC 5737 (192.0.2.0/24) is officially "documentation only" address space, so it is safe to use as the public-internet simulation without any risk of colliding with real assigned space.
Can I change the scheme in my own labs?
Yes. The .yaml files we ship are starting points. Every lab also includes the underlying configurations as a downloadable .txt bundle, so you can swap addresses to fit your own environment. The recipes in the lab guides will still work; just substitute your addresses where ours appear.
Why not use 192.168.x.x for LAN segments?
The 10.20.0.0/24 block is in the same private space and works identically. We picked 10/8 because it gives us room to scale a single lab to a campus-sized address plan without changing the second octet conventions. Real enterprise networks tend to live in 10/8 too.
Where to go next
- CCNA Labs: Network Fundamentals - start here if you are working through the labs library
- CML Free quick-start lab - first time using Cisco Modeling Labs