Many companies ignore DNS, a key component. When DNS has problems, it will cause websites to be inaccessible and emails to be unable to be sent and received, thus affecting the normal operation of the company. If network team members want to deal with DNS problems, they must have a certain understanding of the DNS architecture of their network.
Primary DNS server:
The primary DNS server is the main source of authoritative DNS information for a specific area. It stores the original, accurate and authoritative information of resource records such as domain names and IP addresses in the area. For queries on domain names in the area, the primary DNS server provides the most authoritative and accurate answers.
Secondary DNS server:
The role of the secondary DNS server is to provide backup and load sharing for the primary DNS server. It keeps the data synchronized with the primary server by regularly copying zone data from the primary DNS server. When the primary server fails or the load is too high, the secondary server can take over the DNS query service to ensure the continuity and stability of the DNS service.
Location of the primary and secondary DNS servers:
They can be located in the same data center, distributed in different geographical locations, or even in different network environments. The choice of location usually depends on factors such as network architecture, performance requirements, fault tolerance requirements and cost.
Configuration of primary and secondary DNS servers:
Including the server's IP address, port settings, client range allowed to query, cache settings, etc. The primary server needs to be configured to allow the secondary server to replicate the zone data, while the secondary server needs to be configured with replication intervals, source server addresses and other parameters.
The relationship between the primary and secondary DNS servers:
The primary server is the authoritative source of data, and the secondary server relies on the data update of the primary server. The secondary server regularly requests updates to the zone data from the primary server to maintain data consistency. This relationship ensures the reliability and availability of DNS data, and the secondary server can replace the service when the primary server fails.
DNS zone division:
A DNS zone is a part of the domain name space in the DNS system, which consists of a group of related domain names and corresponding resource records. The purpose of zone division is to facilitate the management and control of DNS data. For example, zones can be divided according to the organization's departments, geographical locations, or business functions.
Domain name resolution strategy:
Refers to the rules and methods for determining how to convert domain names to corresponding IP addresses. This may include giving priority to records in the cache, querying different DNS servers in a specific order, and handling domain name aliases (CNAMEs).
Interaction with external DNS services:
When the local DNS server cannot resolve a domain name, it may be necessary to interact with an external DNS service. This can be done through recursive queries (requesting an external server to complete the entire resolution process and return the final result) or iterative queries (obtaining clues for the next query from one server and completing the resolution step by step). Interaction with external DNS services also involves the establishment of trust relationships, data exchange formats, and security mechanisms.
