Engineering Glossary · Domains
WHOIS Is the First Command When a Name Misbehaves
The site is down, the zone looks correct, and nobody has checked whether the domain is actually in a state that allows it to resolve.
The short answer
WHOIS is the public registration record for a domain: who holds it, through which registrar, in what status, and with which dates attached. RDAP is its modern replacement, returning the same facts as structured JSON you can parse instead of scrape.
For an engineer it is a diagnostic, not a directory. Three fields do most of the work — the registrar of record, the domain status codes, and the expiry date — and between them they explain a large share of the incidents that look at first like a DNS or hosting fault.
By the HostingFast team · Reviewed 12 August 2026
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The record used to publish registrant names, postal addresses and email addresses in the open, which made it an excellent harvesting list. Redaction under privacy law and the spread of proxy services now hide most personal detail by default across much of the namespace.
What survives redaction is the operationally useful part. Creation and expiry dates, the registrar of record, the nameservers on file and the status codes are all still public, and those are precisely the fields you want when something has gone wrong.
Status codes explain the strange outages
A domain in clientHold or serverHold is removed from the zone by the registry: it stops resolving entirely, no matter how correct your records are. Seeing that code turns a baffling total outage into a billing or compliance problem with a known fix.
The transfer-related codes matter for planning rather than for incidents. clientTransferProhibited is the normal, healthy lock you want in place day to day; it is also the thing you must clear before an auth code will get you anywhere.
The command line and the JSON
The classic whois client is still the fastest way to eyeball a record, and its output differs by registry because thin registries hold only a pointer to the registrar while thick ones hold the whole record. That is why the same query answered from two places can look different without either being wrong.
RDAP is the version you can automate. It returns JSON over HTTPS with predictable field names, so a check that would have needed brittle text parsing becomes a couple of lines in a script and a value you can assert on.
Expiry is an availability metric
A lapsed renewal is an outage with a long tail: the name stops resolving, mail stops arriving, and certificate renewal fails alongside everything else. Treat the expiry date as a monitored value rather than a diary entry somebody keeps in their head.
The cheapest useful monitor is a scheduled job that reads the RDAP expiry field for each of your domains and alerts when any of them falls inside your notice period. Cron jobs are available in the panel, so this can live on the same account as the site it protects.
Where the record meets your hosting
The nameservers listed in the record should match the delegation you expect, which makes this a fast cross-check whenever a change does not appear to have taken. If they disagree, the record is right and your assumption is wrong.
Uptime here is a 99.9% target monitored around the clock, and hardware or network faults usually surface through platform monitoring before the first customer notices. A domain that has quietly expired is the one class of outage no host can monitor on your behalf.
Reference material with the command in the text
We wrote these entries the way we would brief a new engineer: what the thing is, which query proves it, and which failure it explains when it goes wrong.
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- 100+ entries, cross-linked throughout
- RDAP and whois, with the difference explained
- Status codes decoded into real symptoms
- Maintained by our own engineers
Why HostingFast
Standard on every plan
A diagnostic, not a directory
This entry treats the record as the first query in an incident rather than as a contact lookup.
Status codes decoded
clientHold, serverHold and the transfer locks, matched to the symptom each one produces.
RDAP for automation
Structured JSON means an expiry check becomes a scheduled job instead of a diary reminder.
Thin against thick registries
Why the same query returns different detail depending on where it is answered.
Expiry treated as uptime
The one outage class your host cannot monitor for you, and how to monitor it yourself.
Continues into its neighbours
Domain Privacy, Domain Registrar and EPP Code carry on from here.
Quick Start
From order to online
- 1
Read the record before the zone
When a domain misbehaves, query the registration record first. Status and delegation will either explain the fault or rule out a whole category in one step.
- 2
Check the status codes
Any hold code means the registry has pulled the name from the zone. No amount of correct DNS will bring it back until that clears.
- 3
Compare listed nameservers with your expectation
If the record disagrees with the panel you have been editing, believe the record and go and fix the delegation.
- 4
Schedule an expiry check
Put a cron job on the account that reads the RDAP expiry for each domain you run and alerts you well before the date arrives.
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Frequently Asked
What people ask us most often
What does a domain status of clientHold actually do?
It removes the domain from the registry zone, so it stops resolving entirely — no records, no mail, no certificate renewal. It is normally applied by a registrar over billing or a verification failure, and no change you make in DNS will work around it. Clear the underlying reason and the name comes back.
Why does the same lookup return different data from different places?
Thin registries hold only a pointer to the registrar of record, so a registry-level query returns a short answer and the registrar-level one returns the detail. Thick registries hold the full record themselves. Add redaction rules that vary by jurisdiction and you get the inconsistency people mistake for stale data.
Can I script a renewal and expiry check?
Yes, and RDAP is the reason it is easy. Request the RDAP record over HTTPS, parse the expiry event out of the JSON, compare it against a threshold and alert. Put that on a cron schedule in the panel and domain expiry stops being something anybody has to remember.
What uptime do you commit to, and what happens in a bad month?
99.9% is the target, monitored around the clock. If a month falls below it because of a fault on our side, our terms entitle you to a pro-rated credit — ask and we apply it. We deliberately call it a target rather than a contractual SLA, and faults normally surface through platform monitoring before a customer reports them.
Keep reading
Domain Registrar
Who publishes the delegation, and the limits that come attached to it.
Domain Name
The hostname itself, and the lookup it costs on a cold cache.
How to Enable WHOIS Privacy
Turning redaction on properly, without breaking the mail you need to receive.
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