Re: Why use DNS for these servers ?

wkevin wrote:
I know that for DNS, NTP and DHCP, we use UDP servers. This is
common practice (and I believe it is so on other operating systems,
besides Linux).
My question is: what is the reason behind it? why not use TCP servers
for DNS or for NTP or for DHCP?

TCP *is* used for DNS, when the response needs more than 1 packet. Otherwise there's 1 UDP packet request, 1 UDP packet response. TCP would be a waste of client resources, server resources, bandwidth, and time just to send 1 data packet in each direction.

Except that NTP and DHCP don't fall back to TCP, the same argument applies to them. Additionally, if the client doesn't have an address yet, TCP without a source address is impossible for DHCP.