Hi I was trying to generate ssh key for a switch

I read that , ssh key is generated as a combination of hostname and domain-name

I created a domain name like test

But doubt is , why isn't the network getting affected when I change domain name

I changed the aggregate level switch's domain name , so now access layer switches and aggregation switch are in two different domain right ? How are they still communicating ?

What is the use of ip domain-name

Thanks in advance

  • Did any answer help you? If so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you can provide and accept your own answer.
    – Ron Maupin
    Commented Dec 25, 2018 at 10:08

2 Answers 2


Domain names are for application-layer protocols. Switches communicate with layer-2 protocols, e.g. ethernet, which know nothing about domain names. The most common layer-1 to 4 protocols (ethernet, Wi-Fi, IPv4, IPv6, TCP, UDP, etc.) use addresses, not names, and they know nothing about names.

IPv4 addresses are 32-bit binary numbers, e.g. 11000110001100110110010011011111, which are hard for humans to read. The IPv4 dotted decimal notation, e.g. is easier for humans to read and understand, but it is still difficult for normal people to remember and relate a bunch of seemingly random IPv4 addresses, even in dotted-decimal notation, to specific services. To help with that, the Domain Names were created to relate more readable names to IP addresses. Basically, it make it easier for you to remember google.com or amazon.com, rather than or

  • Thank you Ron,so if two switches are in differe domain , still they can communicate ?
    – PDHide
    Commented Nov 24, 2018 at 9:55
  • The domains have nothing to do with how switches communicate. Ethernet switches communicate with ethernet, but ethernet knows nothing about domains.
    – Ron Maupin
    Commented Nov 24, 2018 at 17:10

The switches don't care which domains holds DNS (A) records are that point to their management IP addresses.

If SSH is actually used for communication between the switches(?) you usually need to do an initial certificate exchange to establish trust. This is entirely unrelated to DNS.

How the switches communicate is up to the protocol that's used between them. E.g. M/RSTP doesn't use IP at all but BPDUs directly over Ethernet. Where IP is used it's with discovered or configured IP addresses. There's very little use for DNS in a switch.

It's possible that the switch uses information like the configured domain and host names as seeds to generate the public-private key pair for the certificate (although this isn't really smart) but apart from that, those names simply don't matter.

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