add readme

Author: wafuwafu13

check-dns/README.md

@@ -1 +1,55 @@
-# check-dns
+# check-dns
+
+## Description
+
+Monitor DNS response.
+
+## Synopsis
+```
+check-dns -H example.com -s 8.8.8.8
+```
+
+## Installation
+
+First, build this program.
+
+```
+go get github.com/mackerelio/go-check-plugins
+cd $(go env GOPATH)/src/github.com/mackerelio/go-check-plugins/check-dns
+go install
+```
+
+Or you can use this program by installing the official Mackerel package. See [Using the official check plugin pack for check monitoring - Mackerel Docs](https://mackerel.io/docs/entry/howto/mackerel-check-plugins).
+
+
+Next, you can execute this program :-)
+
+```
+check-dns -H example.com -s 8.8.8.8
+```
+
+
+## Setting for mackerel-agent
+
+If there are no problems in the execution result, add a setting in mackerel-agent.conf .
+
+```
+[plugin.checks.fileage-sample]
+command = ["check-dns", "-H", "example.com", "-s", "8.8.8.8"]
+```
+
+## Usage
+### Options
+
+```
+  -H, --host=       The name or address you want to query
+  -s, --server=     DNS server you want to use for the lookup
+  -p, --port=       Port number you want to use (default: 53)
+  -q, --querytype=  DNS record query type where TYPE =(A, AAAA, SRV, TXT, MX, ANY) (default: A)
+  -c, --queryclass= DNS record class type where TYPE =(IN, CS, CH, HS, NONE, ANY) (default: IN)
+      --norec       Set not recursive mode
+```
+
+## For more information
+
+Please execute `check-dns -h` and you can get command line options.