Português
English
The short answer: the SOA (Start of Authority) is the first record in every DNS zone. It names the primary nameserver and the person responsible for the zone, and it carries a serial number plus four timers: they tell secondary nameservers when to fetch the zone again, and tell resolvers how long to remember that a name does not exist. On cPanel hosting the server writes and updates it for you; you read it when you are chasing a change that “does not show up”. If you run a VPS with your own DNS server, keeping it right is your job.
The SOA fields, one by one
| Field | What it means |
| Primary nameserver (MNAME) | The nameserver holding the original copy of the zone. The secondaries copy from it. |
| Responsible person (RNAME) | An e-mail address written with a dot instead of the @: hostmaster.example.com. means hostmaster@example.com. |
| Serial number | The zone’s version. Secondaries only copy the zone when this number goes up. The usual convention is the date followed by a counter: YYYYMMDDnn. |
| Refresh | How often (in seconds) secondaries ask the primary whether the serial has changed. |
| Retry | If that question fails, how long they wait before asking again. |
| Expire | If this much time passes without reaching the primary, the secondaries stop answering for the zone. |
| Minimum (the last number) | Today it does something else: it is how long a resolver keeps the answer “this name does not exist” (negative caching). The lower of this number and the SOA’s own TTL applies. |
Reading and checking the SOA
|
|
|
|
|
| Never lower the serial. If someone types it by hand lower than it was (for example, switching from a plain counter to the date format the wrong way round), the secondaries ignore every change until the number climbs past the old one. There is a proper procedure to fix it (serial arithmetic, from RFC 1982); do not guess, ask for help. |
| The date format is a free clue: with YYYYMMDDnn, one glance tells you the day the zone last changed and how many edits happened that day. It is the quickest answer to “was my change saved?”. |
|
Serial numbers that do not match between nameservers, or a zone that will not update? Tell us the domain and what you changed. Open a support ticket |
RECOMMENDED PRODUCT Web hosting with cPanel Domain and SSL included, daily backups and the panel you already know. from 5.940,00 Kz/mo (3-year plan, with coupon) See plans |
