roblox networking

When to Load

Load when adding a remote, handling untrusted input, implementing cooldowns, or deciding which side owns a result.

Quick Reference

• Treat every client argument as attacker-controlled input.
• Validate type, size, ownership, state, distance, and cooldown on the server.
• Look up prices, damage, rewards, and permissions from server-owned definitions.
• Choose the authority model before designing movement or continuous simulation: Server Authority uses client prediction and server rollback, and is not SetNetworkOwner.
• For simulation input under Server Authority use InputAction/InputContext with RunService:BindToSimulation(), not a RemoteEvent.
• Use events for most gameplay requests. Keep RemoteFunction calls short and bounded.
• Use RemoteEvent for reliable state changes. It is not ordered relative to property or attribute replication: use one explicit state channel or version the state when ordering matters. Reserve UnreliableRemoteEvent for replaceable data such as VFX and snapshots.
• Unreliable is not automatically faster: delivery is unordered, packets may be dropped, and payloads should stay at or below the documented 1000-byte limit.
• Measure payload size and fire rate under load; packet-size estimators are not an official wire-format spec.
• Check numbers for NaN and infinity (x ~= x, math.abs(x) == math.huge) first: NaN defeats </>. Strings: utf8.len(s) catches malformed UTF-8 that fails a DataStore save.
• Serialization decides validation: functions arrive as nil, metatables are stripped, mixed-key tables are mangled, nil in a table truncates the payload, and tables are copies, not references. Validate field by field; share state via server-owned snapshots or ids.
• Server Authority needs Workspace.AuthorityMode = Server plus the full bundle: NextGenerationReplication, PlayerScriptsUseInputActionSystem, deferred SignalBehavior, UseFixedSimulation, StreamingEnabled. Misprediction and rollback are normal (debug surface in full.md).
• Rate limits protect the server; validation still rejects invalid requests.
• Record suspicious behavior with thresholds; never punish one malformed packet.
• Edit-mode play: wrap the network layer so RunContext:IsEdit() gets a local loopback mock (full.md).

Need details? references/full.md has validation, throttling, and mock patterns.