主机命令返回SERVFAIL的原因

Question

我试图为我的博客jfeatures.com和获取错误(SERVFAIL)使用主机命令。我使用谷歌域名的博客，它是由github网页。

$ host jfeatures.com
jfeatures.com has address 185.199.111.153
jfeatures.com has address 185.199.108.153
jfeatures.com has address 185.199.109.153
jfeatures.com has address 185.199.110.153

主机jfeatures.com未找到: 2(SERVFAIL)

jfeatures.com mail is handled by 20 alt2.gmr-smtp-in.l.google.com.
jfeatures.com mail is handled by 40 alt4.gmr-smtp-in.l.google.com.
jfeatures.com mail is handled by 5 gmr-smtp-in.l.google.com.
jfeatures.com mail is handled by 10 alt1.gmr-smtp-in.l.google.com.
jfeatures.com mail is handled by 30 alt3.gmr-smtp-in.l.google.com.
alt2.gmr-smtp-in.l.google.com has address 142.250.141.14
alt4.gmr-smtp-in.l.google.com has address 64.233.171.14
gmr-smtp-in.l.google.com has address 142.251.10.14
alt1.gmr-smtp-in.l.google.com has address 173.194.202.14
alt3.gmr-smtp-in.l.google.com has address 142.250.115.14

如果我指定DNS服务器，它似乎会像预期的那样工作。以下是host jfeatures.com 8.8.8.8的结果

host jfeatures.com 8.8.8.8
Using domain server:
Name: 8.8.8.8
Address: 8.8.8.8#53
Aliases:

jfeatures.com has address 185.199.109.153
jfeatures.com has address 185.199.111.153
jfeatures.com has address 185.199.110.153
jfeatures.com has address 185.199.108.153
jfeatures.com mail is handled by 10 alt1.gmr-smtp-in.l.google.com.
jfeatures.com mail is handled by 30 alt3.gmr-smtp-in.l.google.com.
jfeatures.com mail is handled by 40 alt4.gmr-smtp-in.l.google.com.
jfeatures.com mail is handled by 5 gmr-smtp-in.l.google.com.
jfeatures.com mail is handled by 20 alt2.gmr-smtp-in.l.google.com.

Answer 1

使用host命令上的额外参数，您将绕过通过/etc/resolv.conf定义的默认DNS服务器，特别是使用您提供的服务器：

host jfeatures.com 8.8.8.8    # {domain} {dns_server}

考虑到在指定上游DNS服务器(1.1.1.1、8.8.8.8或9.9.9.9作为已确认的工作替代方案)时不能重现问题，我建议您的上游DNS服务器出现故障。

在国内，这将是您的本地主机或您的ISP自己的服务器。在工作中，它通常是您网络的DNS服务器。根据您想要在识别错误的组件方面参与到多大程度上，您可以通过DNS服务器链进行工作。例如，如果/etc/resolv.conf包含对nameserver 127.0.0.53的引用，则使用systemd-resolved，并且需要检查/run/systemd/resolve/resolv.conf以获得上游DNS服务器的详细信息。否则，使用/etc/resolv.conf本身中的值。