8月12日学习笔记 DNS补充

news2024/9/22 5:33:45

一，DNS工作原理

查询方式

1.递归查询，逐级查询，一次到位，但是速度慢

2.迭代查询，多次查询一个地址，可以缓存一次递归，多次迭代

dig解析域名 yum -y install bind-utils.x86_64

==dig +trace www.baidu.com==

解析.

解析com.

解析baidu.com.

解析www.baidu.com

只要ip地址，不要解析过程

[root@localhost ~]# dig @server www.baidu.com
dig: couldn't get address for 'server': not found
[root@localhost ~]# dig www.baidu.com
; <<>> DiG 9.11.4-P2-RedHat-9.11.4-26.P2.el7_9.16 <<>>
www.baidu.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 36090
;; flags: qr rd ra; QUERY: 1, ANSWER: 3, AUTHORITY: 0,
ADDITIONAL: 0
;; QUESTION SECTION:
;www.baidu.com. IN A
;; ANSWER SECTION:
www.baidu.com. 5 IN CNAME www.a.shifen.com.
www.a.shifen.com. 5 IN A 180.101.50.188
www.a.shifen.com. 5 IN A 180.101.50.242
;; Query time: 78 msec
;; SERVER: 192.168.83.2#53(192.168.83.2)
;; WHEN: 一 7月 22 23:11:22 CST 2024
;; MSG SIZE rcvd: 90

反向解析

[root@localhost ~]# dig -x 180.101.50.188
; <<>> DiG 9.11.4-P2-RedHat-9.11.4-26.P2.el7_9.16 <<>> -x
180.101.50.188
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 6416
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0,
ADDITIONAL: 0
;; QUESTION SECTION:
;188.50.101.180.in-addr.arpa. IN PTR
;; Query time: 73 msec
;; SERVER: 192.168.83.2#53(192.168.83.2)
;; WHEN: 一 7月 22 23:16:32 CST 2024
;; MSG SIZE rcvd: 45

二，客户端进行DNS测试

添加dns服务器

临时

echo "nameserver 10.1.1.11" > /etc/resole.conf

[root@web ~]# echo "nameserver 10.1.1.11" >
/etc/resolv.conf
[root@web ~]#
#临时添加，重启network就还原了

永久

[root@web ~]# vim /etc/sysconfig/network-scripts/ifcfgens33
# 添加dns服务就可以了
DNS:10.1.1.11

检测域名是否正确

[root@web ~]# ping www.yuanyu.zhangmin
PING www.yuanyu.zhangmin (10.1.1.12) 56(84) bytes of data.
64 bytes from web.yuanyu.zhangmin (10.1.1.12): icmp_seq=1
ttl=64 time=0.011 ms
64 bytes from web.yuanyu.zhangmin (10.1.1.12): icmp_seq=2
ttl=64 time=0.026 ms
64 bytes from web.yuanyu.zhangmin (10.1.1.12): icmp_seq=3
ttl=64 time=0.022 ms
64 bytes from web.yuanyu.zhangmin (10.1.1.12): icmp_seq=4
ttl=64 time=0.043 ms
64 bytes from web.yuanyu.zhangmin (10.1.1.12): icmp_seq=5
ttl=64 time=0.022 ms
64 bytes from web.yuanyu.zhangmin (10.1.1.12): icmp_seq=6
ttl=64 time=0.015 ms
64 bytes from web.yuanyu.zhangmin (10.1.1.12): icmp_seq=7
ttl=64 time=0.022 ms
64 bytes from web.yuanyu.zhangmin (10.1.1.12): icmp_seq=8
ttl=64 time=0.021 ms
64 bytes from web.yuanyu.zhangmin (10.1.1.12): icmp_seq=9
ttl=64 time=0.022 ms
^C
--- www.yuanyu.zhangmin ping statistics ---
9 packets transmitted, 9 received, 0% packet loss, time
8007ms
rtt min/avg/max/mdev = 0.011/0.022/0.043/0.010 ms
[root@web ~]#
curl www.yuanyu.zhangmin
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01
Transitional//EN">
<html>
<head>
<title>Welcome to CentOS</title>
<style rel="stylesheet" type="text/css">
[root@web ~]# yum -y install elinks.x86_64