[ntp:questions] (Software) timeserver for windows being broadcast-able incl. keys

Tom Smith smith at cag.zko.hp.com
Tue Mar 13 22:39:16 UTC 2007

Erik wrote:
> - the command line to be used:   broadcast address [key key | autokey]
> [version version] [minpoll minpoll] [ttl ttl]

This means you need:

    broadcast [broadcast-address] key [keynumber]

Add "version 3" to the end if your clients are exclusively running
NTP V3 (unlikely).

> - still not quite clear which address I should use here: the subnet
> the machines are connected to?
> They are on two subnets: and

These are netmasks, not subnets, and not broadcast addresses
for a subnet. The broadcast address is the network address
masked by the netmask and with all 1's at the end where the
netmask is all 0's. If your subnet is, for example, the
addresses 192.168.3.[0-127] with a netmask of,
the broadcast address is Think of the
broadcast address as the last address in the subnet.

> And because of this confusion, also confusion on the following:
> - a broadcast can not go beyond the subnet
> "Ordinarily, this technology does not operate beyond the first hop
> router or gateway"
> a multicast can and - although this also uses the "broadcast" command
> - on the client-side it requires multicastclient (instead of
> broadcastclient which is what I have to use. "Have to" since client-
> config can not be altered)
> Does this mean that I ran into a problem here

This is about multicast and the limitations of broadcast. Your clients
are not using multicast and they are using broadcast, so don't
worry about it.

> - With the server I can broadcast just one key (with the "broadcast"
> command)


> Do you have any idea why (in the ntp.keys-file on all clients) more
> than one key is specified?

You'll have to ask whomever put them there. Presumably because
at one time different keys were used for different purposes
somebody thought they would be.

Why don't you just look at how the previous server was configured
(the one that was in use by the existing clients) and copy that?

> Hope you can give me a hint so I can go further
> Kind regards
> Erik

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