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The main purpose of a DHCP server is to provide dynamic configuration for a group of hosts (mainly IP, Gateway and DNS). There are several options that can also be sent.

Option 12 (client hostname), which is supported by Cisco devices, doesn't make sense to me. I tried it. I set this option ON and set the value to "Tom". Then you can see that all hosts got the same name, which is "Tom".

In which scenarios would I need to set all hosts to the same exact name? What is the importance of such a thing?

  • Why do you think every host should get the exact same name? This option is used so the server can tell each client their unique name, it should be used as a client specific configuration option. – Teun Vink Jan 17 at 7:30
  • I tried it with real devices, and the clients got the same exact name, – AhmedWas Jan 17 at 7:31
  • If you configure it as a global setting, of course they would. – Teun Vink Jan 17 at 7:31
  • Gloabl setting? You mean I can make non-global settings for each client, or what do you mean? Thanks in advance. – AhmedWas Jan 17 at 7:33
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    Yes, you can make client specific settings, like the assigned IP address and host name. – Teun Vink Jan 17 at 7:48
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You wouldn't set this option on the whole scope. Rather, you'd set it for a reserved address, so that a specific host gets a defined IP address and a defined host name.

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It's more usual for DHCP clients to use option 12 to tell the server their hostname.

Some DHCP clients may use this client-provided hostname to automatically populate the DNS server with an A record for the client, using that hostname. Although that may be considered a security risk.

  • ... and that security risk can be mitigated by having the DHCP server generate the required DDNS update (optionally signed) which is being sent to the DNS server (determined by looking up the parent domain's SOA DNS record), possibly after some sanity checking before doing so. – Marc 'netztier' Luethi Feb 1 at 6:13

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