CentOS Stream 9 经常无法解析域名

[YaoYaooo]

有没有 linux 服务器大佬帮忙看看问题：

我有一台电脑装的 CentOS Stream 9 服务器无 GUI 版，网线直连的路由器，设置了固定 ip 。

网络好的，可以内网连接，也可以访问外网。搭了 PHP 和 Apache 运行着。

但问题是，时不时的就网络错误，表现为：

[PDOException] SQLSTATE[HY000] [2002] php_network_getaddresses: getaddrinfo failed: Name or service not known

或

cURL Error (6) Could not resolve host: xx.xx.com （此处我改了域名 xx ）

他也不是一直不行，就是偶尔，大概 10 分钟左右就会出现一次错误

# cat /etc/NetworkManager/system-connections/enp4s0.nmconnection
[connection]
id=enp4s0
uuid=(UUID here)
type=ethernet
interface-name=enp4s0
timestamp=1712230701

[ethernet]

[ipv4]
address1=192.168.2.120/24,192.168.2.1
dns=192.168.2.1;114.114.114.114;8.8.8.8;
method=manual

[ipv6]
addr-gen-mode=eui64
method=auto

[proxy]

# cat /etc/resolv.conf
# Generated by NetworkManager
nameserver 192.168.2.1
nameserver 114.114.114.114
nameserver 8.8.8.8

# cat /etc/nsswitch.conf | grep 'hosts'
#     hosts: files dns
#     hosts: files dns  # from user file
# Valid databases are: aliases, ethers, group, gshadow, hosts,
hosts:      files dns myhostname

# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: enp4s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 58:11:22:bd:ae:31 brd ff:ff:ff:ff:ff:ff
    inet 192.168.2.120/24 brd 192.168.2.255 scope global noprefixroute enp4s0
       valid_lft forever preferred_lft forever
    inet6 fe80::5a11:22ff:febd:ae31/64 scope link noprefixroute
       valid_lft forever preferred_lft forever
3: wlo1: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group default qlen 1000
    link/ether f4:26:79:f6:9d:43 brd ff:ff:ff:ff:ff:ff
    altname wlp0s20f3

另外一个情况是：dns=192.168.2.1;114.114.114.114;8.8.8.8; 这里如果我不填 192.168.2.1 或把他移到后面，则完全连不上外网（内网是可以）！

[ysc3839]

出问题时试试用 dig 直接请求 192.168.2.1 看看吧

[littleylv]

@ysc3839
你好，我是问问题的本人。你说的这个方法好像不大好实现，因为出问题的时候是“偶然”的，很难把握那个瞬间马上去 dig

[ysc3839]

@littleylv 那建议加重试机制，这个感觉是 192.168.2.1 服务偶然超时导致的

[perfectlife]

写个脚本循环 dig 并打印时间 ，然后 dns 出问题了 去查看

[littleylv]

@perfectlife
```
#!/bin/bash
while true
do
sleep 1
date
dig 192.168.2.1
done
```
有道理，准备跑看看

[littleylv]

@ysc3839
@perfectlife
老哥们，我执行
dig 192.168.2.1
dig www.baidu.com
的结果，麻烦帮忙看看

N 次的正常返回结果如下：
; <<>> DiG 9.16.23-RH <<>> 192.168.2.1
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 12297
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
;; QUESTION SECTION:
;192.168.2.1. IN A

;; AUTHORITY SECTION:
. 199 IN SOA a.root-servers.net. nstld.verisign-grs.com. 2024040701 1800 900 604800 86400

;; Query time: 13 msec
;; SERVER: 192.168.2.1#53(192.168.2.1)
;; WHEN: Mon Apr 08 11:31:04 CST 2024
;; MSG SIZE rcvd: 115


; <<>> DiG 9.16.23-RH <<>> www.baidu.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 33348
;; flags: qr aa ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 0
;; WARNING: Message has 23 extra bytes at end

;; QUESTION SECTION:
;www.baidu.com. IN A

;; ANSWER SECTION:
www.baidu.com. 202 IN A 180.101.50.242
www.baidu.com. 202 IN A 180.101.50.188

;; Query time: 2 msec
;; SERVER: 192.168.2.1#53(192.168.2.1)
;; WHEN: Mon Apr 08 11:31:04 CST 2024
;; MSG SIZE rcvd: 86

其中某一次出问题的结果：
; <<>> DiG 9.16.23-RH <<>> 192.168.2.1
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 16660
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
;; QUESTION SECTION:
;192.168.2.1. IN A

;; AUTHORITY SECTION:
. 198 IN SOA a.root-servers.net. nstld.verisign-grs.com. 2024040701 1800 900 604800 86400

;; Query time: 20 msec
;; SERVER: 192.168.2.1#53(192.168.2.1)
;; WHEN: Mon Apr 08 11:31:05 CST 2024
;; MSG SIZE rcvd: 115

;; Warning: Message parser reports malformed message packet.
;; ;; Question section mismatch: got www.b\000idu.com/A/IN
;; ;; Question section mismatch: got www.b\000idu.com/A/IN
;; reply from unexpected source: 192.168.2.1#37994, expected 223.5.5.5#53

;; reply from unexpected source: 192.168.2.1#19320, expected 223.6.6.6#53

;; Warning: Message parser reports malformed message packet.
;; ;; Question section mismatch: got www.b\000idu.com/A/IN
;; ;; Question section mismatch: got www.b\000idu.com/A/IN
;; reply from unexpected source: 192.168.2.1#37994, expected 223.5.5.5#53

;; reply from unexpected source: 192.168.2.1#19320, expected 223.6.6.6#53

;; Warning: Message parser reports malformed message packet.
;; ;; Question section mismatch: got www.b\000idu.com/A/IN
;; ;; Question section mismatch: got www.b\000idu.com/A/IN
;; reply from unexpected source: 192.168.2.1#37994, expected 223.5.5.5#53

;; reply from unexpected source: 192.168.2.1#19320, expected 223.6.6.6#53


; <<>> DiG 9.16.23-RH <<>> www.baidu.com
;; global options: +cmd
;; connection timed out; no servers could be reached