AI Answer Library

Our data cannot leave the internal network — can we still use large language models?

Short answer

Yes — this is exactly what self-hosting exists for. Download open weights into your network, run inference on local GPUs, and no part of the process requires internet access or phones anything home. The catch is that "stays inside" has to hold for the entire chain: the vector store, logs, monitoring and alerting, even the fonts and CDN assets your front end loads. Localising the model while everything around it still talks to the public internet defeats the purpose.

Key points

  • 01Open weights running locally need no outbound connection. A model is a set of parameter files with no telemetry inside — and you can verify that yourself with a packet capture.
  • 02The risk is not the model but everything around it: telemetry, crash-reporting SDKs, on-demand package installs and CDN-hosted fonts are the usual accidental egress paths.
  • 03Fully offline operation works but must be planned: weights, dependency images and security patches all have to be ferried in through an approved channel, and operations look nothing like a connected environment.
  • 04Data residency comes in degrees. Most companies actually mean "customer data and core assets must not leave", not "the machine is physically air-gapped". Clarify the requirement before over-engineering.
  • 05Offline is not the same as secure. An internal deployment still needs access isolation, audit logs and output traceability, or you have merely traded external leakage for internal over-access.

Auditing the chain: where data can slip out

In an on-premise build, the model is rarely what leaks — the components around it that default to being online are. The table below breaks a typical RAG deployment into segments and states the default behaviour alongside the offline approach. A practical acceptance test: tighten outbound firewall rules to an allowlist, then run a full business flow and see what gets blocked.

Segment of the chainLeaves the network by default?How to keep it internalMost commonly missed
Model inferenceNo — local weights on a local serving stack need no connectionDownload weights offline and distribute from an internal registryAnonymous usage stats and version checks in the serving framework left enabled
Embedding model and vector storeDepends — managed vector services do leave the networkServe the embedding model locally and pick a self-hostable vector databaseThe model is local while the vector store is still a hosted instance
Logs, monitoring and crash reportingYes — most observability SDKs report to the vendor by defaultSwitch to a self-hosted stack and disable third-party reportingStack traces carrying the raw user question shipped to a public endpoint
Dependencies and container imagesYes — builds and upgrades pull from the internet by defaultRun an internal registry and ferry images and packages in offlineNormally offline, then one urgent upgrade reopens external access
Front-end static assetsYes — CDN-hosted fonts and scripts carry referrer informationBundle fonts, icons and scripts locallyDiscovered only when an internal page fails to load a public font
Model and security updatesYes — the standing pain point of any offline environmentBatch transfers on a schedule, with a rollback pathNo update cadence, so after a year the stack is full of known CVEs

Clarify what "cannot leave the network" actually means

The phrase means very different things at different companies, and the cost gap between those meanings is several-fold. The strictest tier is physical isolation: no external network at all, every transfer approved and carried on media — typical for classified environments and some industrial control settings. The middle tier is logical isolation: connectivity exists but is governed, egress runs through an allowlist, and sensitive data may not leave a defined zone. The loosest tier is really "no third-party model vendor": data may move within your own cloud account, it just must not reach a public model API. Deployment shape, cost and operational complexity differ completely across the three. The common waste is designing for the strictest tier when the actual requirement is the third. Writing that single sentence down before signing matters more than any later technical choice.

Three problems an internal deployment still has to solve

First, permissions. The model has no notion of who should not see what, and pouring every company document into one vector store effectively grants everyone full-corpus search. Filter by user identity at the retrieval layer; never encode permission logic in a prompt. Second, traceability. Who asked what and when, which documents were cited and what conclusion was produced all need to be queryable, or incidents cannot be reconstructed and audits will fail. Third, the capability ceiling. Internally you can only run what fits in your VRAM, and on harder reasoning tasks an open model will trail the latest hosted flagship. That is the real price of self-hosting, and it should be stated plainly during selection rather than discovered after launch as "it is not as smart as we expected".

Where this applies

When this answer does not hold

  • Local model serving does not by itself make the system compliant. If logs, monitoring or front-end assets still reach the internet, data leaks indirectly — run a full egress audit at acceptance.
  • Regulators define data egress differently by sector. In some, redacted data under a signed processing agreement may legally reach an external API — defer to your own regulator's definition.
  • Fully offline environments cost noticeably more to maintain, especially for security patches and model refreshes. Without a transfer process and an update cadence, going offline accumulates security debt instead.
  • This covers inference deployment. Training or full-parameter fine-tuning inside the network has entirely different compute, storage and annotation requirements and cannot be sized from this answer.

People also ask

  • Can an LLM be deployed in an air-gapped internal network?
  • How do you build an AI knowledge base when data must stay on-premise?
  • Does a self-hosted LLM really send nothing back to the vendor?
  • Can organisations handling classified information use LLMs at all?
  • Can an AI assistant run on servers with no internet access?
Written by: YGG Technology Solutions TeamPublished: 2026-08-01Last reviewed: 2026-08-01