DNS Lookup Chain Error Block for React

No. The hops, their times and the names are typed in the file: fieldcrew.example and portal.fieldcrew.example resolve, and every other well-formed address stops at the root server (FAIL_AT). The walk is a chain of 150 ms timeouts that starts when you press Run the check and ends when it reaches its stop. To wire it, call your resolver or a lookup endpoint from the handler and fill the hops from what it returns.

The check validates on press, never disabling the button: an empty field gets "Enter an address to check.", something that isn't a host name gets "Enter an address like fieldcrew.example.", and either way focus goes to the field. Typing clears the sentence. The field is read-only while the walk runs, and the address is shown left to right even on a right-to-left page.

Because a lookup really passes through them: the device's own cache, the network's resolver, the provider's resolver, the root servers and the server that holds the record. Where it stops tells you who to ask: a failure at the first hops points to the device or the network, one at the root or the authoritative server points to the name itself. Edit STEPS to change the chain and FAIL_AT to move the failing hop.

By shape and word: a solid square and a time for a hop that answered, a cross and "No answer" for the one that didn't, a dash and "Not reached" for those after it, a dashed circle and "Waiting" for those still to come, and a spinning dashed circle for the one being asked. The failing hop's name stays in the text color; its cross is the only status color.

Tab reaches the address and Run the check; Enter in the address runs it too. While it walks, a polite status message says "Checking northharbor.example…", and when it stops focus moves to the result line, which names the host and the hop that had no answer, because the busy button drops focus. The hops are an ordered list, so a screen reader reads each name and its state in order.

The two halves stack, with the address and Run the check first so the button is on the first screen, and the chain below under its own rule. The hop names and their times keep one row each down to 320 px.