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dns

dns

github.com/chatermCloud & DevOps5982 installsUpdated 34w ago
Repository

About dns

dns is a skill for DNS configuration and troubleshooting, aimed at people managing name resolution and DNS servers. It covers common query tools, local settings, and BIND and CoreDNS examples.

Key features

  1. 01Query with dig, nslookup, and host
  2. 02Configure local DNS settings
  3. 03Set up BIND zones and records
  4. 04Write CoreDNS configuration
  5. 05Troubleshoot resolution, cache, and performance

Use cases

  1. 01Diagnose failed or slow name resolution
  2. 02Flush the local DNS cache
  3. 03Configure internal name resolution
  4. 04Check DNS servers and ports

Install

Copy the command and run it in a terminal.

$npx skills add https://github.com/chaterm/terminal-skills --skill dns

After installing, type/dnsin Claude Code to confirm it loaded.

Details

From the project README

DNS 配置与排查

概述

DNS 配置、解析排查、BIND/CoreDNS 等技能。

DNS 查询工具

dig
# 基础查询
dig example.com
dig example.com A
dig example.com AAAA
dig example.com MX
dig example.com NS
dig example.com TXT
dig example.com ANY

# 简短输出
dig +short example.com

# 指定 DNS 服务器
dig @8.8.8.8 example.com
dig @1.1.1.1 example.com

# 追踪解析过程
dig +trace example.com

# 反向解析
dig -x 8.8.8.8

# 查询特定记录
dig example.com SOA
dig example.com CNAME

# 禁用递归
dig +norecurse example.com
nslookup
# 基础查询
nslookup example.com
nslookup example.com 8.8.8.8

# 查询特定类型
nslookup -type=mx example.com
nslookup -type=ns example.com
nslookup -type=txt example.com

# 反向解析
nslookup 8.8.8.8
host
# 基础查询
host example.com
host -t mx example.com
host -t ns example.com

# 反向解析
host 8.8.8.8

# 详细输出
host -v example.com

本地 DNS 配置

/etc/resolv.conf
# 查看配置
cat /etc/resolv.conf

# 配置示例
nameserver 8.8.8.8
nameserver 8.8.4.4
search example.com
options timeout:2 attempts:3

# 临时修改（可能被覆盖）
echo "nameserver 8.8.8.8" > /etc/resolv.conf
/etc/hosts
# 查看
cat /etc/hosts

# 添加记录
echo "192.168.1.100 myserver.local" >> /etc/hosts

# 格式
127.0.0.1       localhost
192.168.1.100   myserver myserver.local
systemd-resolved
# 查看状态
systemd-resolve --status
resolvectl status

# 查询
resolvectl query example.com

# 刷新缓存
systemd-resolve --flush-caches
resolvectl flush-caches

# 配置文件
/etc/systemd/resolved.conf

BIND DNS 服务器

安装与管理
# 安装
apt install bind9 bind9utils          # Debian/Ubuntu
yum install bind bind-utils           # CentOS/RHEL

# 服务管理
systemctl start named
systemctl enable named
systemctl status named

# 检查配置
named-checkconf
named-checkzone example.com /etc/bind/zones/db.example.com
主配置
# /etc/bind/named.conf.options
options {
    directory "/var/cache/bind";
    
    forwarders {
        8.8.8.8;
        8.8.4.4;
    };
    
    dnssec-validation auto;
    
    listen-on { any; };
    listen-on-v6 { any; };
    
    allow-query { any; };
    allow-recursion { 192.168.0.0/16; 10.0.0.0/8; };
    
    recursion yes;
};
区域配置
# /etc/bind/named.conf.local
zone "example.com" {
    type master;
    file "/etc/bind/zones/db.example.com";
    allow-transfer { 192.168.1.2; };
};

zone "1.168.192.in-addr.arpa" {
    type master;
    file "/etc/bind/zones/db.192.168.1";
};
区域文件
# /etc/bind/zones/db.example.com
$TTL    604800
@       IN      SOA     ns1.example.com. admin.example.com. (
                        2024011501      ; Serial
                        604800          ; Refresh
                        86400           ; Retry
                        2419200         ; Expire
                        604800 )        ; Negative Cache TTL

; Name servers
@       IN      NS      ns1.example.com.
@       IN      NS      ns2.example.com.

; A records
@       IN      A       192.168.1.10
ns1     IN      A       192.168.1.1
ns2     IN      A       192.168.1.2
www     IN      A       192.168.1.10
mail    IN      A       192.168.1.20

; CNAME records
ftp     IN      CNAME   www.example.com.

; MX records
@       IN      MX      10 mail.example.com.

CoreDNS

配置文件
# Corefile
.:53 {
    forward . 8.8.8.8 8.8.4.4
    cache 30
    log
    errors
}

example.com:53 {
    file /etc/coredns/db.example.com
    log
    errors
}
Kubernetes CoreDNS
# ConfigMap
apiVersion: v1
kind: ConfigMap
metadata:
  name: coredns
  namespace: kube-system
data:
  Corefile: |
    .:53 {
        errors
        health {
            lameduck 5s
        }
        ready
        kubernetes cluster.local in-addr.arpa ip6.arpa {
            pods insecure
            fallthrough in-addr.arpa ip6.arpa
            ttl 30
        }
        prometheus :9153
        forward . /etc/resolv.conf {
            max_concurrent 1000
        }
        cache 30
        loop
        reload
        loadbalance
    }

常见场景

场景 1：DNS 解析排查
# 1. 检查本地配置
cat /etc/resolv.conf

# 2. 测试 DNS 服务器连通性
ping 8.8.8.8

# 3. 查询解析
dig example.com
dig @8.8.8.8 example.com

# 4. 追踪解析路径
dig +trace example.com

# 5. 检查 DNS 缓存
systemd-resolve --statistics
场景 2：清除 DNS 缓存
# systemd-resolved
systemd-resolve --flush-caches

# nscd
systemctl restart nscd

# dnsmasq
systemctl restart dnsmasq

# BIND
rndc flush

# macOS
sudo dscacheutil -flushcache
sudo killall -HUP mDNSResponder
场景 3：测试 DNS 性能
# 使用 dig 测试响应时间
dig example.com | grep "Query time"

# 批量测试
for i in {1..10}; do
    dig +noall +stats example.com | grep "Query time"
done

# 使用 dnsperf
dnsperf -s 8.8.8.8 -d queries.txt
场景 4：配置内部 DNS
# 添加内部域名解析
# /etc/hosts
192.168.1.100   app.internal
192.168.1.101   db.internal

# 或配置 dnsmasq
# /etc/dnsmasq.conf
address=/internal/192.168.1.100
server=8.8.8.8

故障排查

问题排查方法
解析失败检查 resolv.conf、DNS 服务器
解析慢检查 DNS 服务器响应、网络延迟
缓存问题清除本地缓存、检查 TTL
记录不存在检查区域文件、SOA 序列号
# 检查 DNS 端口
ss -ulnp | grep :53
netstat -ulnp | grep :53

# 测试 TCP/UDP
dig +tcp example.com
dig +notcp example.com

# 检查 BIND 日志
tail -f /var/log/named/query.log
journalctl -u named -f

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