RTK Query caching is built on two separate mechanisms that work together. The first is the cache lifetime: every endpoint’s data is stored in a normalized cache, and the keepUnusedDataFor option controls how long an unused entry survives before it is removed. The second is the tag system: the providesTags and invalidatesTags options connect the…
An endpoint is the definition of a single data operation inside an API slice. The build.query method defines a read operation, and the build.mutation method defines a write operation. The previous chapter covered the createApi setup and the store integration; this chapter covers the endpoints themselves: the query function, the argument type, the return type,…
RTK Query is the data-fetching and caching layer built into Redux Toolkit. It is not a separate library; it is an additional addon that ships with @reduxjs/toolkit, and it leverages the same slice and middleware architecture that the previous chapters covered . The setup is a single createApi call that defines the base URL, the…
An entity adapter is a set of prebuilt reducers and selectors for managing a normalized collection of items in the store. The previous chapters covered slices, thunks, and the async lifecycle. This chapter covers the structure that the store uses for collections of entities with IDs—users, todos, posts, comments—and the adapter that generates the CRUD…
A thunk is not limited to one action. The payload creator of a createAsyncThunk receives the thunkAPI object, which includes dispatch, and the thunk can dispatch any number of other actions before, during, or after the async operation. The previous chapters covered the three lifecycle actions that createAsyncThunk generates automatically; this chapter covers the actions…
Traffic control is the kernel subsystem that decides how packets are queued, scheduled, shaped, and dropped as they leave or enter a network interface. The previous chapters covered the firewall, which decides whether a packet is allowed to pass; this chapter covers the subsystem that decides when and how fast it passes. The LFCE exam…
The previous chapter established what ipset is and why it exists. This chapter is the operational sequence. It covers the commands that create a set, populate it, reference it from iptables, and make it survive a reboot. The configuration is simple on its surface—a set is created, addresses are added, and a rule matches against…
ipset is a kernel framework and userspace utility for storing collections of IP addresses, networks, ports, and other values in indexed data structures—hash tables or bitmaps—so that iptables can match against the entire collection with a single rule instead of a long chain of individual rules . The previous chapters covered the iptables rules that…
Destination NAT is the mechanism that publishes an internal service on a public address. A client connects to the router’s public IP and port, and the router rewrites the destination to the internal server’s private address and port before forwarding the packet. The previous chapter covered source NAT, which rewrites the source of outgoing packets;…
The previous chapter covered NAT concepts: the difference between source NAT and destination NAT, the connection-tracking requirement, and the role of the nat table. This chapter focuses on the source-NAT side: the two mechanisms that rewrite the source address of outgoing packets, the choice between them, and the Linux configuration for each. The snat statement…