This is an original planning guide. It is not a vendor manual, an official standard, or legal advice. Example addresses use documentation ranges. Review every command before you paste it.
What this hour is for
Resolution is the path from a stub resolver to a recursive resolver and then to the authoritative servers. The lookup and the trace show the answers they receive for a name you type. example.com is the documentation name.
A trace is not a zone transfer and not a list of every name in a domain. You look up one name. You do not walk a zone you do not administer.
Write which resolver you used. A public resolver and the resolver you operate are different choices. The answer you saw is a cache result at that moment, not a permanent map of the internet.
Do not change a zone from this page. The record, if it is wrong, belongs to the admin of that zone.
The change you can finish
Apply nothing during the writing of the note. When the lab window opens, it is one change on the device named in the ticket. Read the draft, then the device, then decide.
Rollback is the file or the revision you saved first. You do not invent a rollback after the only copy is gone.
- Pick one name you may look up.
- Note the resolver.
- Read the trace.
- Write the answer you saw.
- Do not request a zone transfer.
- Do not edit a zone.
Mistakes that outlive the command
How DNS Resolution Works goes wrong in a small set of ways. The list is here so the ticket can forbid them before the window.
- An AXFR because the trace was interesting.
- Walking every name in a domain.
- Changing a zone you do not administer.
- Treating a cached answer as permanent.
- A resolver chosen to evade a network you do not administer.
Decisions to write down
One decision for How DNS Resolution Works: One name was looked up. The resolver is named. No zone transfer was requested. No zone was edited. And the answer is labeled as what you saw.
Checks before you call it done
Confirm this before you call the change done: The name is written. The resolver is written. The answer is written. No AXFR was run. And no zone file was changed. If one of those fails, stop.
Before you leave the device
How DNS Resolution Works ends when the hostname on the device matches the hostname in the ticket. If it does not, you are on the wrong box. Stop. A command that succeeded on the wrong box is not progress.
The draft stays a draft until a person has read the names in it. A generator does not log into the device and does not know which interface is the uplink. You delete a line that names a device, a zone, or a prefix you did not write down.
0.0.0.0/0 is not kept because a sample included it. A source you can say is the source you keep. 192.0.2.0/24, 198.51.100.0/24, 203.0.113.0/24, and 2001:db8::/32 are documentation. They belong in the note. They are not prefixes you type onto a production device because they appeared in a draft.
prompt-for-this is a reminder that a secret is missing. It is not a password, a key, a community string, or a pre-shared key you save in the ticket or in git. The real secret stays in the store.
One change is the window. A VLAN and a routing protocol and a VPN do not share it. If two things move and the result is wrong, you will not know which one did it. The next feature waits for its own page.
If the same step fails twice, stop for the day. The failure is the result. Adding a forum command beside a half-applied config produces a device nobody can rebuild. Restore the copy you took first.
A second person reads the device name and the change aloud. If they cannot find them in the ticket, the note is not done. Silence is not agreement. Then leave the device alone.
This page is a planning guide. It is not a vendor manual, not an official standard, and not a permission to touch a network you do not administer. The pillar guide owns the wider design. This page owns one lab proof.
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