docs: capture DNS resilience and Technitium backup sync
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Fizzlepoof
@@ -17,7 +17,7 @@ Central index for all homelab infrastructure documentation.
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| [Architecture Overview](architecture/ARCHITECTURE_OVERVIEW.md) | Full stack diagram and service map |
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| [Services Directory](architecture/SERVICES_DIRECTORY.md) | All services with hosts, ports, and status |
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| [Network Map](architecture/NETWORK.md) | VLANs, Tailscale, DNS |
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| [Networking Model](architecture/NETWORKING_MODEL.md) | VLANs, firewall policy, DHCP DNS, and remote access |
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| [AI Services Network](architecture/AI_SERVICES_NETWORK.md) | Cross-stack Docker networking for AI services |
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## Stacks
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@@ -35,3 +35,12 @@ Central index for all homelab infrastructure documentation.
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| [Expansion Plan](planning/HOMELAB_EXPANSION_PLAN.md) | 6-phase buildout — all phases complete as of 2026-05-06 |
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| [TODO](planning/TODO.md) | Active and backlog tasks |
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## Operations
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| File | Description |
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|------|-------------|
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| [DNS Resilience](operations/DNS_RESILIENCE.md) | Technitium backup-node topology, PD sync automation, fallback semantics, and validation SOP |
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| [Backup Policy](operations/BACKUP_POLICY.md) | Backup scope, database dumps, and restore cadence |
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| [PD Backup Deployment](operations/PD_BACKUP_DEPLOYMENT.md) | Live PD backup runner deployment details |
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| [Secrets Management](operations/SECRETS_MANAGEMENT.md) | `.env` handling, encrypted backups, and incident guardrails |
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@@ -23,8 +23,9 @@ Full homelab stack as of 2026-05-09. All 6 expansion phases are complete and dep
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- **UniFi policy zones:** `Internal` = Management + Trusted + Servers, `Untrusted` = IoT + Cameras + Old IoT, `Hotspot` = Guest
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- **Current custom firewall hardening:** `Allow Internal to Untrusted`, `Block Untrusted to Gateway Admin Surfaces`, `Allow Untrusted to DNS Resolver`, `Block Untrusted to Gateway Default Services`, `Allow Untrusted to Gateway DHCP`, `Allow Untrusted to Gateway mDNS`, plus explicit public-DNS allows used for fallback
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- **Current DHCP DNS policy:** `Management`, `Trusted`, `Servers`, `IoT`, `Camera`, and `Old IoT` advertise the Technitium trio `10.5.30.8`, `10.5.30.9`, and `10.5.30.10`, followed by external fallback `9.9.9.9`; `Guest` advertises `9.9.9.9` and `1.1.1.1`
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- **Net effect:** every non-guest lane now has three independent internal Technitium resolvers for both public DNS and the private `home.paccoco.com` zone, plus external fallback if all homelab resolvers are down; untrusted lanes still retain DNS, DHCP, and mDNS but no longer have general gateway access or UDM Pro admin-surface access
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- **Current DNS caveat:** the backup Technitium nodes on N.O.M.A.D. (`10.5.30.9`) and Serenity (`10.5.30.10`) start from a cloned PD Technitium config, so future authoritative-zone changes on PD must be resynced or automated to keep all three nodes aligned
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- **Net effect:** every non-guest lane now has three independent internal Technitium resolvers for both public DNS and the private `home.paccoco.com` zone, plus external fallback for general internet name resolution if all homelab resolvers are down; untrusted lanes still retain DNS, DHCP, and mDNS but no longer have general gateway access or UDM Pro admin-surface access
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- **Current sync model:** PD (`10.5.30.8`) is the authoritative Technitium source, and root cron on PD runs `/mnt/docker-ssd/docker/compose/technitium-pilot/bin/sync_backup_nodes.sh` every 15 minutes to rsync the live config to N.O.M.A.D. (`10.5.30.9`) and Serenity (`10.5.30.10`), restart those backup stacks, and verify both private and public DNS answers
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- **Current DNS caveats:** `9.9.9.9` preserves public DNS continuity but is not an authoritative substitute for the internal `home.paccoco.com` zone; same-host macvlan tests are also misleading, so resolver verification must come from an off-host client or peer host
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- **Tailscale:** Serenity reachable at 100.94.87.79
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- **NFS:** Serenity exports `/mnt/user/data` and `/mnt/user/immich` → mounted on PD at `/mnt/unraid/` via post-init script
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- **Docker networking:** Cross-stack communication via named external networks (`ai-services`, `ix-databases_shared-databases`)
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@@ -31,8 +31,9 @@
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- **Current DHCP DNS policy:**
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- `Management`, `Trusted`, `Servers`, `IoT`, `Camera`, and `Old IoT` advertise `10.5.30.8`, `10.5.30.9`, `10.5.30.10`, and `9.9.9.9` via DHCP
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- `Guest` advertises `9.9.9.9` and `1.1.1.1`
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- **Current hardening result:** every non-guest lane now has three internal Technitium resolvers for both public DNS and the private `home.paccoco.com` zone, plus an external fallback; IoT/Camera/Old IoT keep DNS, DHCP, and mDNS, but general `Untrusted -> Gateway` access and UDM Pro admin-surface access are blocked
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- **Current DNS caveat:** the N.O.M.A.D. (`10.5.30.9`) and Serenity (`10.5.30.10`) Technitium backups are seeded from a cloned PD config. Any future authoritative-zone changes on PD must be resynced or automated so all three resolvers stay aligned
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- **Current hardening result:** every non-guest lane now has three internal Technitium resolvers for both public DNS and the private `home.paccoco.com` zone, plus an external fallback for general internet name resolution; IoT/Camera/Old IoT keep DNS, DHCP, and mDNS, but general `Untrusted -> Gateway` access and UDM Pro admin-surface access are blocked
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- **Current sync model:** PD (`10.5.30.8`) is the Technitium source of truth, and root cron on PD runs `/mnt/docker-ssd/docker/compose/technitium-pilot/bin/sync_backup_nodes.sh` every 15 minutes to push the live config to N.O.M.A.D. (`10.5.30.9`) and Serenity (`10.5.30.10`), restart those backup nodes, and verify both `dns.home.paccoco.com` and a public recursive lookup
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- **Current DNS caveats:** `9.9.9.9` is only a public-DNS fallback and does not preserve authoritative internal-zone behavior by itself; same-host checks against macvlan IPs are not reliable, so health verification must come from another host or client on the LAN/VLAN
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- **Serenity IP:** 10.5.30.5
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- **N.O.M.A.D. IP:** 10.5.30.7
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- **PlausibleDeniability:** 10.5.30.6 (Servers VLAN)
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129
docs/operations/DNS_RESILIENCE.md
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129
docs/operations/DNS_RESILIENCE.md
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# DNS Resilience
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Current homelab DNS resilience model after the single-node outage lesson.
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## Problem Statement
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When Technitium on PD died, clients that depended on that single internal resolver lost DNS. Public internet connectivity did not matter because name resolution was gone first.
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The fix was to stop treating DNS as a single-host service and advertise multiple internal resolvers across the important LANs.
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## Current Resolver Topology
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| Resolver | Host | Service role | Resolver IP |
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|----------|------|--------------|-------------|
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| PD Technitium | PlausibleDeniability | primary live source of truth | `10.5.30.8` |
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| Nomad Technitium | N.O.M.A.D. | backup internal resolver | `10.5.30.9` |
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| Serenity Technitium | Serenity | backup internal resolver | `10.5.30.10` |
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| Quad9 | external | public-DNS fallback only | `9.9.9.9` |
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All three Technitium nodes serve:
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- recursive public DNS
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- the private authoritative zone `home.paccoco.com`
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## DHCP Advertisement Policy
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UniFi DHCP currently advertises the Technitium trio plus an external fallback on:
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- `Management`
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- `Trusted`
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- `Servers`
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- `IoT`
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- `Camera`
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- `Old IoT`
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Advertised order:
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1. `10.5.30.8`
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2. `10.5.30.9`
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3. `10.5.30.10`
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4. `9.9.9.9`
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`Guest` remains public-only:
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- `9.9.9.9`
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- `1.1.1.1`
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## What This Fixes
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- A single Technitium host failure no longer wipes DNS for Trusted or Servers clients.
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- Internal-zone continuity now survives the loss of any one Technitium node, as long as at least one of the remaining Technitium nodes is healthy.
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- Public DNS continuity still exists even if the whole internal Technitium trio is down, because clients also have `9.9.9.9`.
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## Important Limits
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### External fallback is not full internal-DNS continuity
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`9.9.9.9` is only a public fallback.
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It can preserve general internet resolution if all internal resolvers die, but it does not replace the authoritative internal `home.paccoco.com` zone behavior.
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Operationally: if all three Technitium nodes are down, clients may still resolve public domains, but private homelab names may be missing or semantically wrong.
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### Macvlan health checks are deceptive
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These Technitium nodes use dedicated macvlan IPs.
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That means a host often cannot reliably query its own resolver IP:
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- PD may fail to query `10.5.30.8` from the PD host itself
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- NOMAD may fail to query `10.5.30.9` from NOMAD itself
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- Serenity may fail to query `10.5.30.10` from Serenity itself
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Do not treat same-host DNS failures as proof that the resolver is down.
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Use an off-host probe from another LAN host or client.
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## Current Sync Model
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PD is the authoritative Technitium source of truth.
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Live sync runner:
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- path: `/mnt/docker-ssd/docker/compose/technitium-pilot/bin/sync_backup_nodes.sh`
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Live schedule:
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- root cron on PD every 15 minutes
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Log path:
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- `/mnt/tank/docker/appdata/technitium-pilot/logs/sync-backup-nodes.log`
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The runner does all of the following:
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1. rsync the live PD Technitium config to NOMAD and Serenity
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2. exclude rebuildable cache/stats/blocklist artifacts
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3. restart the backup stacks
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4. verify a private authoritative answer for `dns.home.paccoco.com`
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5. verify a public recursive answer for `cloudflare.com`
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6. stamp each backup with `last_pd_sync_utc.txt`
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## Validation SOP
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When verifying DNS resilience, check from the correct network context.
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Minimum proof:
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1. confirm UniFi DHCP advertises `10.5.30.8`, `10.5.30.9`, `10.5.30.10`, and `9.9.9.9` on the intended VLANs
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2. from an off-host client or peer host, query each internal resolver directly for:
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- `dns.home.paccoco.com A`
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- `cloudflare.com A`
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3. confirm the PD sync cron exists
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4. inspect the latest sync log for successful Nomad and Serenity verification
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Recommended direct checks:
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- `dig @10.5.30.8 dns.home.paccoco.com A`
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- `dig @10.5.30.9 dns.home.paccoco.com A`
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- `dig @10.5.30.10 dns.home.paccoco.com A`
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- `dig @10.5.30.8 cloudflare.com A`
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- `dig @10.5.30.9 cloudflare.com A`
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- `dig @10.5.30.10 cloudflare.com A`
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## Operator Guidance
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- If internal-zone records change on PD, the backups should pick them up automatically within 15 minutes.
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- If the sync log shows failures, treat that as an internal-zone resilience regression even if public DNS still works.
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- If testing from the host that owns the macvlan IP fails, repeat the test from another host before escalating.
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- Keep at least one external fallback in DHCP for non-guest lanes.
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## Source Paths
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- Repo stack docs:
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- `technitium-pilot/README.md`
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- `technitium-nomad/README.md`
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- `technitium-serenity/README.md`
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- Architecture docs:
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- `docs/architecture/ARCHITECTURE_OVERVIEW.md`
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- `docs/architecture/NETWORKING_MODEL.md`
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@@ -199,6 +199,13 @@ These are expected to be managed by Wings/Pelican rather than a local compose fi
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- Topic thumbs write back to `doris-digest/data/feedback.json`.
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- Paperless acknowledge/dismiss state writes to `/opt/doris-dashboard/data/paperless_review_state.json` on the live host.
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### Technitium Backup Resolver
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- Live stack path: `/opt/technitium-nomad`
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- Resolver bind IP: `10.5.30.9`
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- Role: active DHCP-advertised backup Technitium resolver for the homelab
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- Config is refreshed from PD's live Technitium directory by the PD-side sync runner every 15 minutes
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- Same-host checks from NOMAD to `10.5.30.9` are unreliable because the resolver sits behind macvlan networking; verify from another LAN peer instead
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### MeshCore to MQTT relay
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- Install date: 2026-05-18
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- Install root: `/opt/mctomqtt`
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@@ -53,6 +53,12 @@ Current light-tier notes:
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- Pangolin VPS + Newt for external services
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- SSH from Windows 11
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## DNS Role
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- Primary Technitium source-of-truth node binds `10.5.30.8` via the `technitium-pilot` stack
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- Root cron runs `/mnt/docker-ssd/docker/compose/technitium-pilot/bin/sync_backup_nodes.sh` every 15 minutes to push the live Technitium config to the backup nodes on N.O.M.A.D. (`10.5.30.9`) and Serenity (`10.5.30.10`)
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- Sync logs live at `/mnt/tank/docker/appdata/technitium-pilot/logs/sync-backup-nodes.log`
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- External fallback `9.9.9.9` protects public DNS continuity, but authoritative `home.paccoco.com` answers still depend on at least one Technitium node being up
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## NFS Mounts (from Serenity)
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- Serenity `/mnt/user/data` → `/mnt/unraid/data` (media libraries)
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- Serenity `/mnt/user/immich` → `/mnt/unraid/immich` (Immich photo library)
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@@ -53,6 +53,15 @@ Text Embeddings Inference reranker for OpenWebUI RAG pipeline.
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Managed via Unraid Community Apps. See Unraid dashboard for individual service ports and status.
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### Technitium Backup Resolver
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Serenity hosts the secondary backup Technitium node on `10.5.30.10`.
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- Live stack path: `/mnt/user/appdata/technitium-serenity`
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- Resolver bind IP: `10.5.30.10`
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- Config is refreshed from PD's live Technitium directory by the PD-side sync runner every 15 minutes
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- Same-host checks from Serenity to `10.5.30.10` are unreliable because the resolver sits behind macvlan networking; verify from another LAN peer instead
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## Notes
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- No GPU; reranker uses CPU-only TEI image
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