doc: dns monitoring help document

home/docs/help/dns.md

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+---
+id: dns
+Title: Monitoring DNS     
+sidebar_label: DNS Monitor
+keywords: [open source monitoring tool, open source dns monitoring tool, monitoring dns metrics]
+---
+
+> Collect and monitor the general performance metrics by `dig` command.
+
+## Pre-monitoring operations
+
+If you want to monitor DNS server, you need to understand what is `dig` command and the output of `dig` command.
+
+**Here's the example of executing dig command**
+
+```shell
+dig www.google.com
+```
+
+
+### Configure parameters
+
+| Parameter name | Parameter Help describes the |
+| ------------ |------------------------------------------------------|
+| DNS Server IP | THE MONITORED PEER IPV4, IPV6 OR DOMAIN NAME. Note ⚠️ that there are no protocol headers (eg: https://, http://). |
+| Task Name | A name that identifies this monitoring that needs to be unique. |
+| Port | The default port provided by DNS server is 53. |
+| Address For DNS | Used for dig command, it is an address that interact with DNS server. |
+| Connect Timeout(ms) | Timeout for dig command. |
+| Use TCP Protocol | Connect to DNS server using tcp, default is udp. |
+| Intervals(s) | Monitor the periodic data acquisition interval, in seconds, and the minimum interval that can be set is 30 seconds |
+| Description | For more information identifying and describing the remarks for this monitoring, users can remark the information here |
+
+
+### Collect metrics
+
+#### Header
+
+| Metric Name | metric unit | Metrics help describe |
+| ------------------ | -------- |--------------------------------|
+| Response Time | ms | DNS server response time |
+| Opcode | None | operation code of dig command |
+| Response Status | None | status of DNS server resolving address |
+| Response Flags | None | flags of DNS server resolving address |
+| Question Record Count | None | Question record count of dig output |
+| Answer Record Count | None | Answer record count of dig output |
+| Authority Record Count | None | Authority record count of dig output |
+| Additional Record Count | None | Additional record count of dig output |
+
+#### Question
+
+| Metric Name | metric unit | Metrics help describe |
+|---------| -------- |----------------------------|
+| Section     | None        | section of Question record |
+
+#### Answer/Authority/Additional
+
+> Depanding on DNS config, Answer/Authority/Additional can be multi records for one address. Each record will be showd as a section here. Default is 10 sections.
+
+| Metric Name | metric unit | Metrics help describe |
+| ----------- | ----------- | --------------------- |
+| Section0    | None        | section of record     |
+| Section1    | None        | section of record     |
+| Section2    | None        | section of record     |
+| Section3    | None        | section of record     |
+| Section4    | None        | section of record     |
+| Section5    | None        | section of record     |
+| Section6    | None        | section of record     |
+| Section7    | None        | section of record     |
+| Section8    | None        | section of record     |
+| Section9    | None        | section of record     |
+
+
+