Secondary DNS zone and dynamic updates

Question

If a client is pointed to a DNS server that is hosting a secondary zone that is only read only, and it needs to republish its dns record does it follow the SOA ip to do it or how does this work with secondary zones?

Answer 1

Hi Mishaua

In the case of a DNS client pointing to a DNS server that hosts a secondary zone, the process of republishing DNS records works as follows:

1. DNS Zone Transfer: The secondary DNS server obtains a copy of the zone data from the primary DNS server using a process called zone transfer. The primary DNS server is the authoritative server for the zone, while the secondary DNS server maintains a read-only copy.
2. Updating DNS Records: When a DNS client needs to update its DNS records within the zone, it does not directly communicate with the secondary DNS server. Instead, it contacts the primary DNS server, which is responsible for accepting and processing DNS record updates.
3. SOA Record: The Start of Authority (SOA) record in the DNS zone specifies the primary DNS server's IP address and contains essential information about the zone, including the serial number, refresh interval, and retry interval.
4. DNS Record Update Process: When the DNS client sends a request to update its DNS record, the primary DNS server receives the update and increments the serial number in the SOA record. This change indicates that the zone has been modified.
5. Zone Transfer to Secondary DNS Servers: The primary DNS server notifies the secondary DNS servers about the zone update by sending a notification message. The secondary DNS servers then initiate a zone transfer process with the primary DNS server to obtain the updated zone data.
6. Republishing DNS Records: Once the secondary DNS servers have received the updated zone data, they publish the updated DNS records to their clients during subsequent DNS queries. The clients querying the secondary DNS servers will receive the latest DNS record information as retrieved from the primary DNS server.

In summary, the DNS client points to the primary DNS server for DNS record updates, and the secondary DNS servers automatically obtain the updated zone data through zone transfers initiated by the primary DNS server. The secondary DNS servers then provide the updated DNS records to the clients during DNS queries.

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