If a site or email isn't working after a DNS change, dig and nslookup tell you exactly what the internet currently sees for your domain, straight from the source. Run dig yourdomain.com (or nslookup yourdomain.com on Windows) and compare the answer against what you set in your DNS Zone Editor. If they match, the record is live and the problem is somewhere else, usually a local or ISP cache. If they don't match, you're just waiting on propagation.
Using dig
dig is available on macOS and Linux by default. The basic form:
dig yourdomain.com
Look at the ANSWER SECTION. It shows the record type, TTL, and the current value. For example:
yourdomain.com. 3600 IN A 192.0.2.1
That number is the TTL in seconds, the time resolvers will cache this answer before checking again. The exact value depends on what's set for that record in your zone. To query a specific record type, add it after the domain:
dig yourdomain.com MX dig yourdomain.com TXT dig www.yourdomain.com CNAME
To see who's actually answering the query, check the SERVER line near the bottom of the output. By default dig asks whatever resolver your machine is configured to use, which might be your router, your ISP, or a public resolver. That matters because different resolvers can have different cached answers mid-propagation, as explained in how long DNS propagation takes.
To bypass your local resolver's cache and ask a specific server directly, use @:
dig @1.1.1.1 yourdomain.com dig @8.8.8.8 yourdomain.com
This is the fastest way to check whether a change has reached a major public resolver, without waiting for your own ISP to catch up.
Checking your nameservers directly
If you want the authoritative answer, straight from the nameserver, skip caching resolvers entirely:
dig @ns1.flashcloud.com yourdomain.com A
If our nameservers already show the new value but public resolvers don't yet, the change is correct and you're just waiting on caches to expire elsewhere.
To confirm which nameservers a domain is actually using:
dig yourdomain.com NS
If this doesn't list ns1.flashcloud.com and ns2.flashcloud.com, DNS record edits need to happen at whatever provider does appear here, not in our DNS Zone Editor. If you're researching DNSSEC, see DNSSEC: what it is and whether you need it.
Using nslookup
nslookup ships on Windows, macOS, and most Linux distributions, and it's the more familiar tool if you're not comfortable with dig's output. Basic query:
nslookup yourdomain.com
The output is split into a "Server" block (which resolver answered) and an "Answer" or "Non-authoritative answer" block (the actual record). Query a specific type with -type:
nslookup -type=MX yourdomain.com nslookup -type=TXT yourdomain.com nslookup -type=NS yourdomain.com
To query against a specific server instead of your default resolver, add it as a second argument:
nslookup yourdomain.com 1.1.1.1
nslookup doesn't show TTL by default the way dig does, which is one reason sysadmins tend to prefer dig for anything beyond a quick sanity check. But for confirming "does this A record resolve at all," either tool gets you the answer in seconds.
Reading the result
Once you have output from either tool, there are really only three outcomes:
- The value matches what you set. DNS is correct. Any remaining issue (site not loading, mail not arriving) is downstream of DNS, not caused by it.
- The value is old or missing. The change hasn't propagated to the resolver you queried yet. Try a different public resolver, or wait and re-check.
- NXDOMAIN or no answer at all. Either the record doesn't exist, the domain isn't using the nameservers you expect, or there's a typo in the name you queried.
If you flushed your local DNS cache and a public resolver like 1.1.1.1 still shows the old value well past the record's TTL, that's worth a closer look rather than more waiting.
When to contact support
If dig @ns1.flashcloud.com shows the wrong value for a record you edited in the DNS Zone Editor, or a record you added isn't showing up there at all, open a ticket from Support in the portal. Include the exact dig or nslookup output you're seeing so a human can compare it against what's actually in the zone.