Primary-Secondary
Redundant DNS Servers: These are backup DNS servers that ensure continuous availability and reliability by taking over if the primary DNS server fails.
Primary DNS Server
This server holds all the zone information for a domain and is responsible for making and storing updates to the domain's DNS records.
ns1.example.com
is the primary DNS server for example.com
.
Secondary DNS Server
This server receives a read-only copy of the zone information from the primary DNS server and helps distribute the load and provide redundancy. It gets updates via zone transfers from the primary server.
If ns1.example.com
is the primary DNS server, ns2.example.com
could be the secondary DNS server for the example.com
domain.
Zone Information
This is the data associated with a domain, including DNS records such as A records (IP addresses), MX records (mail servers), and CNAME records (canonical names).
Zone Transfer
This is the process by which a secondary DNS server receives a copy of the zone information from the primary DNS server. It can be a full transfer (AXFR) or incremental transfer (IXFR).
Invisibility
Primary and secondary DNS servers are invisible to end users because they operate in the background to translate domain names into IP addresses automatically. Users interact with domain names and websites directly, while DNS servers handle the resolution process behind the scenes. Local caching on users' devices also reduces the need to frequently query DNS servers, making their role seamless and unnoticed.
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