Question

主要是我想使用nslookup检测是否在计算机上正确配置了DNS。遗憾的是，当nslookup无法查找条目时，它仍然会返回成功错误代码。此外，不同的查询可能会返回多个结果，这使得测试更加困难。

所以我想编写一个bash片段，如果dns条目成功解析，它会返回成功。如果我得到多个结果，我不在乎。

示例nslookup -type=srv _ldap._tcp.DOMAIN.COM

Answer 1

正确的解决方案是使用挖掘和测试是否有任何带有短选项的文本：

[ "$(dig +short -t srv _ldap._tcp.example.com.)" ] && echo "got answer"

Answer 2

Agree the fact, nslookup, returns 0 for both successful and failing DNS look-ups. You can achieve what you are trying to do, but post-processing the output of the command.

You can put up a dnsLookup.sh script with something like

#!/bin/bash

# Checking for the resolved IP address from the end of the command output. Refer
# the normal command output of nslookup to understand why.

resolvedIP=$(nslookup "$1" | awk -F':' '/^Address: / { matched = 1 } matched { print $2}' | xargs)

# Deciding the lookup status by checking the variable has a valid IP string

[[ -z "$resolvedIP" ]] && echo "$1" lookup failure || echo "$1" resolved to "$resolvedIP"

Running for some sample URL's

dudeOnMac:~$ ./dnsLookup.sh www.google.com
www.google.com resolved to 206.78.111.12
dudeOnMac:~$ ./dnsLookup.sh www.googlejunkaddress.com
www.googlejunkaddress.com lookup failure

Answer 3

诀窍是使用host | grep命令而不是nslookup，因为这个命令不那么冗长，使得用grep解析更加容易。

如果DNS解析失败，这是一个失败的命令：

host -t srv _ldap._tcp.EXAMPLE.COM | grep "has SRV record" >/dev/null ||     {
    echo "FATAL: Unable to locate ldap servers, probably you are not on intranet or your DNS servers are broken."
    exit 2
}

注意：正如您可以看到我的示例特定于SRV查询，但您可以轻松调整更改参数和grep过滤器以使其与其他人一起使用。

如何在bash中使用nslookup来验证是否正确配置了DNS？

3 个答案: