Two-Node Setup Guide

How to set up and run the simulator across two VMs — the way the real remote EX200 is laid out. node1 is the controller: you drive everything from it, and it seeds, grades, and controls node2 over SSH.

All simulator commands run as root inside the VMs (sudo -i). virsh/snapshot commands run on the hypervisor host.

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Prerequisites

• Two disposable VMs, both the same RHEL version — either RHEL 9 or RHEL 10 (or Rocky / AlmaLinux / CentOS Stream 9|10). The simulator detects the version and serves RHCSA 9 or RHCSA 10 automatically; both nodes must match so the two-node paper is the same version on each. Building the second as a clone of the first is easiest.
• Each VM: ~2 GB RAM and one blank spare disk (e.g. /dev/vdb) for the storage tasks.
• The matching install DVD ISO attached to each VM (the offline package source).
• The two VMs are on the same network and can reach each other by IP.
• You know each VM's IP (ip -4 addr inside the VM). This guide uses:
  • node1 = 192.168.100.10
  • node2 = 192.168.100.11

💡 Take a snapshot of each VM before you start. Reverting a snapshot is the fastest, most reliable way to reset.

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Step 1 — Copy the simulator to both VMs

On each VM, get the project (git clone, or scp the folder), e.g.:

git clone https://github.com/ambawatyuvaraj/rhcsa-exam-simulator.git
cd rhcsa-exam-simulator

Step 2 — Passwordless root SSH: node1 → node2

The grading channel needs node1 to reach node2's root account by key (it then sets up a dedicated rhcsactl grading account automatically). Set this up once:

On node1 (as root) — create a key and print it:

[ -f /root/.ssh/id_ed25519 ] || ssh-keygen -t ed25519 -N '' -f /root/.ssh/id_ed25519
cat /root/.ssh/id_ed25519.pub

On node2 (as root) — trust that key:

mkdir -p /root/.ssh && chmod 700 /root/.ssh
echo 'PASTE-node1-root-public-key-here' >> /root/.ssh/authorized_keys
chmod 600 /root/.ssh/authorized_keys
restorecon -RF /root/.ssh 2>/dev/null

Back on node1, confirm it works with no password prompt:

ssh root@192.168.100.11 hostname     # should print node2's hostname, no password

(Key-based root login is allowed by default on RHEL 9 — you do not need to change PermitRootLogin.)

Step 3 — Install the simulator on both VMs

On each VM (DVD attached), as root:

sudo ./install.sh          # installs the 'rhcsa-sim' CLI + configures the offline DVD repo

Step 4 — Pair the two nodes

Declare each VM's role and its peer's IP. Run on both:

# on node1  (peer = node2's IP)
sudo rhcsa-sim node-setup --role node1 --peer 192.168.100.11

# on node2  (peer = node1's IP)
sudo rhcsa-sim node-setup --role node2 --peer 192.168.100.10

This sets each hostname (node1.example.com / node2.example.com), writes the /etc/hosts entries, and creates the rhcsactl grading account.

Step 5 — Verify

Run on both — everything must be GREEN:

sudo rhcsa-sim doctor

On node1 you should see controller channel to node2 works. If not, see Troubleshooting.

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Step 6 — Start a two-node exam (from node1)

Everything is driven from node1:

sudo rhcsa-sim start exam-2node-01    # seeds BOTH nodes (node1 locally, node2 over SSH)

Pick any two-node paper with rhcsa-sim list (exam-2node-01 … exam-2node-08).

Step 7 — Open the paper and do the tasks

sudo rhcsa-sim tui        # browser "Test Exam" view (add --text for the terminal view)

The paper shows both nodes' task groups.

• Do node1 tasks on node1.
• For node2 tasks, connect to node2 and become root:

  ssh student@node2.example.com
  sudo -i
  

  (node2's first task is usually recovering its own lost root password — do that on node2's console, not over SSH.)
• The browser's VM control panel manages node2 (status / reboot / console / rebuild), like the real exam's VM manager.

Step 8 — Grade

From node1, grade both nodes at once:

sudo rhcsa-sim grade --reboot     # reboots + grades both, then prints one combined /300 score

--reboot is the persistence test (like the real exam). For a quick check without rebooting, use sudo rhcsa-sim grade. See the full breakdown with sudo rhcsa-sim report --combined.

Step 9 — Reset between attempts

sudo rhcsa-sim reset      # on node1 — wipes changes on BOTH nodes back to clean

Or revert both VMs' snapshots from the hypervisor (the most reliable reset). A shut-off node2 must be powered back on from the hypervisor before you grade.

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Troubleshooting

• controller channel to node2 ... not set up — re-run node-setup on both VMs, then re-check Step 2 (from node1, ssh root@<node2-ip> hostname must work with no password). Re-run sudo rhcsa-sim doctor.
• peer node2 not reachable — the VMs can't see each other. Check they're on the same network and ping 192.168.100.11 works from node1.
• Storage tasks can't find a disk — attach a blank spare disk to each VM (the real exam provides /dev/vdb).
• Package tasks fail offline — the DVD isn't mounted as the repo; run sudo rhcsa-sim local-repo on that VM.
• node2 won't power on from the browser — a guest can't start a shut-off peer; power it on from your hypervisor (virsh start node2).