grceng.academy
YAML lab 40 bonus XP

Repair the scanner address record

Start labRead the room

Objectives

The scanner inventory lists a host at 192.168.10.70/26, but the operator copied a /24 mask into the change request and marked private addressing as proof of isolation. The host and approved prefix are authoritative; the copied mask and security claim are not.

Complete the YAML with the approved prefix, exact subnet boundaries, ordinary broadcast-subnet host capacity, address category, and an evidence source that could substantiate the segmentation claim. The evidence field asks for the artefact type, not an invented filename.

Scanner installation record

host: 192.168.10.70
approved_prefix: 26
copied_mask: 255.255.255.0
claim: private addressing proves isolation
subnet_type: ordinary broadcast LAN

Checks the server runs (6)

  • Prefix and mask match the approved design
  • Network boundary contains the scanner
  • Broadcast closes the correct block
  • Host capacity excludes reserved endpoints
  • Address category does not overclaim isolation
  • Evidence names an enforcement artefact

Check names are all you see here: the expectations that decide pass or fail, and the reference solution, stay on the server.

Step-by-step hints

The guided walkthrough, in full. It is free: no XP cost, and it does not touch the paid hint ladder or the reveal gate.

  1. Step 1

    Anchor the bit boundary

    Find the authoritative prefix in the record. Convert its contiguous network bits into decimal mask octets rather than copying the operator's mask.

    Prefix and mask match the approved design

  2. Step 2

    Locate both ends

    Find the aligned block containing the host. Its first address identifies the network, and setting all host bits closes the block.

    Network boundary contains the scannerBroadcast closes the correct block

  3. Step 3

    Count assignable positions

    Count combinations in the host portion, then account for the endpoint reservations specified by the subnet type.

    Host capacity excludes reserved endpoints

  4. Step 4

    Separate naming from protection

    Compare the address against the reserved ranges. Decide whether belonging to that category itself enforces separation, and name an artefact showing actual traffic enforcement.

    Address category does not overclaim isolationEvidence names an enforcement artefact

Rules summary

  • XP on pass

    40 bonus XP the first time every check goes green.

  • Paid hints

    2 available. Each costs 25% of the lab XP (about 10 XP).

  • Reveal solution

    Scores 0 XP and unlocks only after 3 check runs.

  • Attempt cap

    60 check runs per learner. The runner warns you in the last 10.

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  • Walkthrough

    Always free and never penalised: use it before spending a hint.