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Why can't DNS create multiple A records with different names using the same IP?

gh X 50 Reputation points
2023-10-13T03:23:16.7033333+00:00

The following was translated by DeepL

Example: There is an IP 192.168.9.9 which is both a www server (www.xyz.cn) and an ftp server (ftp.xyz.cn).

Question 1.

Why can't DNS create multiple A records with different names for the same IP? Instead, it needs to use CNAME to create them? As in the following two images.图片1

图片2

Question 2.

After creating an ftp with CNAME, when I need to reverse query, how can I query the ftp domain name of 192.168.9.9?

Thanks for your help!
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  1. Anonymous
    2023-10-13T22:41:26.9133333+00:00

    You can't. A CName is an alias. When you do a DNS look up on a CName, you get back the hostname, not an ip address. You'll need to do 2 lookups to get the ip address. CName -> MachineName -> ip address. A single A record "MachineName" can have MULTIPLE CNames that point to it.

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