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

gh X 30 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!


Windows Server 2019
Windows Server 2019
A Microsoft server operating system that supports enterprise-level management updated to data storage.
3,507 questions
Windows Server
Windows Server
A family of Microsoft server operating systems that support enterprise-level management, data storage, applications, and communications.
12,289 questions
0 comments No comments
{count} votes

1 answer

Sort by: Most helpful
  1. Dave Patrick 426.2K Reputation points MVP
    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.

    --please don't forget to close up the thread here by marking answer if the reply is helpful--