Online Tool Store
DNS Record Generator
Generate formatted A, CNAME, MX, TXT, SPF, and CAA records with trailing dots fixed, CNAME-at-root blocked, and long TXT/SPF values split at 255 bytes.
🔒 This tool runs entirely in your browser. Your files are never uploaded to a server.
How the DNS Record Generator works
- Choose the record type — the fields change to match what that type actually needs.
- Enter the host and value; CNAME and MX targets get the trailing dot added automatically if you leave it off.
- Pick a TTL — low while you are making changes, higher once settled — then copy or download the finished record.
The method
A name ending in a dot is absolute; one without a dot is relative and gets the zone name appended, which is the cause of most broken records.
mx1.provider.net. (correct) vs mx1.provider.net → mx1.provider.net.example.com
Many hosting panels add the dot for you, and adding it yourself in those panels breaks the record — check how yours behaves before pasting. CAA values are the one exception: real-world provider convention writes those without a trailing dot, e.g. `0 issue "letsencrypt.org"`, so the generator leaves them as typed.
FAQ
Why can there be only one SPF record?
Because a receiving server that finds two TXT SPF records treats the result as permanently failing. Merge every sender into a single record with multiple include statements.
What TTL should I use before a migration?
Drop it to 300 seconds at least a full old-TTL period before the change, so caches expire quickly during the cutover. Raise it again afterwards.
Can a CNAME sit at the domain root?
Not in standard DNS — the root needs SOA and NS records, which a CNAME cannot coexist with. Providers offer ALIAS or ANAME records to work around it. The generator blocks this combination directly rather than only mentioning it here.
Why did my TXT value get split into multiple quoted strings?
A single TXT character-string is limited to 255 bytes by RFC 1035 — this is a DNS protocol limit, not a bug. A longer value (a common issue with DKIM keys) is split into multiple quoted strings, which resolvers concatenate back together automatically when read.
What do the CAA flag and tag mean?
The flag is 0 for normal, or 128 to mark the record "critical" so certificate authorities must refuse issuance if they don't understand the tag. The tag is "issue" for standard certificates, "issuewild" for wildcard certificates specifically (you need both if you use wildcards), or "iodef" to name a mailto: or https: address for violation reports. To block all issuance, use tag "issue" with value ";".
Can an MX record point to a CNAME?
No — RFC 2181 prohibits it, and many mail servers reject delivery if it does. Point MX at a hostname that has its own A/AAAA record instead. The generator does not check this the way it blocks CNAME at the zone root, since that other record lives elsewhere in your zone, outside what a single MX entry can see.
Does this tool check my domain's live DNS?
No. It only formats the record you type — it does not query your domain or any nameserver. That makes it usable before a domain even resolves, but you are responsible for pasting the finished record into your actual DNS host.
How we compare
| Feature | Online Tool Store | MxToolbox SPF Generator | Ultra Web Hosting CAA Generator |
|---|---|---|---|
| Covers A, CNAME, MX, TXT/SPF and CAA in one tool | ✓ | SPF only | CAA only |
| No live DNS lookup needed — works before the domain even resolves | ✓ | Looks up your domain's existing record | ✓ |
| Trailing dot handled automatically | ✓ | N/A — SPF values aren't domain names | N/A — CAA values aren't written with one |
| Blocks CNAME at the zone root, with the reason why | ✓ | N/A | N/A |
| Splits long TXT/SPF values at the 255-byte limit automatically | ✓ | Not mentioned | N/A |
| No account | ✓ | ✓ | ✓ |
DNS Record Generator is built around the two failures that cost hours: a missing trailing dot and a second SPF record.