Why does my new record not show up?

Because a resolver is still serving the cached old answer until its TTL runs out. Check the TTL on the record you replaced: that is how long the wait can be. Switching resolvers here often shows the change arriving at one before the other.

What is the difference between this and asking my registrar?

Your registrar shows what you have set. This shows what the world currently sees, which is the same thing only once the change has spread. When the two disagree, the difference is time.

Not by us, because there is nothing here to log it. The query goes from your browser to Cloudflare or Google, and both publish what they keep: Cloudflare states it discards query data within 24 hours and does not sell it.

Can I look up a subdomain?

Yes. Type it in full, such as mail.example.com. Records live on exact names, so a record on the root domain says nothing about a subdomain and the other way round.

DNS Lookup

Type a domain and read its records. The common types are fetched together, so you see the addresses, the mail servers and the text records in one answer rather than one lookup at a time.

The domain you type is sent to Cloudflare or Google's public resolver, which answers the query. Nothing is stored here and nothing else leaves your browser.

How to use DNS Lookup

1Type a domain name, or paste a URL and let the host be taken out of it.
2Leave the record type on the common ones, or pick a single type.
3Press look up.
4Read the records, their values and how long they are cached for.

Which record answers which question

A and AAAA are the addresses a name points at, IPv4 and IPv6. CNAME means the name is an alias for another name, and a CNAME cannot sit alongside other records on the same name, which is why a root domain usually cannot be one.

MX says where mail goes, lowest priority first. TXT is free text and has become the place everything else lives: SPF, DMARC, domain verification strings for half a dozen services. NS lists the nameservers that are authoritative, and SOA carries the zone's serial number and its timers.

CAA is the one most people have never set. It names the certificate authorities allowed to issue for the domain, and an empty CAA set means any of them may.

TTL, and why a change has not appeared yet

Every record comes with a time to live, which is how long a resolver may keep the answer before asking again. A record with a TTL of 24 hours can keep serving the old value for a full day after you change it, however many times you check.

The TTL shown here is the one remaining on the resolver's copy, counting down, rather than the value you set. Seeing it fall and then jump back to the full figure is the moment the resolver fetched the record again.

Who answers the question

A browser has no way to ask a nameserver directly, so these queries go to Cloudflare or Google over HTTPS. You can switch between them, which is worth doing when an answer looks wrong: two resolvers disagreeing usually means a change is still spreading, and both agreeing means it has arrived.

Neither is the authoritative source. For the definitive answer, ask the domain's own nameservers, which the NS records here will name.

Limits

Answers come from a public resolver's cache, not from the domain's own nameservers, so a very recent change may not show yet.
No DNSSEC validation detail beyond what the resolver reports.
No zone transfers, and no way to list every record a domain has. DNS has no such query.
A query for a record type a domain does not use returns nothing, which is a normal answer rather than an error.

Frequently asked questions

Why does my new record not show up?: Because a resolver is still serving the cached old answer until its TTL runs out. Check the TTL on the record you replaced: that is how long the wait can be. Switching resolvers here often shows the change arriving at one before the other.
What is the difference between this and asking my registrar?: Your registrar shows what you have set. This shows what the world currently sees, which is the same thing only once the change has spread. When the two disagree, the difference is time.
Is my lookup logged?: Not by us, because there is nothing here to log it. The query goes from your browser to Cloudflare or Google, and both publish what they keep: Cloudflare states it discards query data within 24 hours and does not sell it.
Can I look up a subdomain?: Yes. Type it in full, such as mail.example.com. Records live on exact names, so a record on the root domain says nothing about a subdomain and the other way round.