DHCP Option 51

RouterOS General
1

Hi
Can I specify DHCP Lease Time through DHCP Option 51 in Mikrotik DHCP Server instead of specifying Lease-Time directly in DHCP Server ?

BR

2

I would like to know the same. It means, I am trying to set an option (code 51) for DHCP option set but it does not work for me. Static leases clients with selected option set still uses predefined lease time value from DHCP server. Maybe I do no know the right format for the time in that option?

I have tried values in “Value” field like:
‘1h’
‘00:60:00’
‘01:00:00’
‘00 01:00:00’

but nothing works for me :frowning: RouterOS 6.48.2

3

On static dhcp leases already is present lease-time.

If you want change lease time to be different to dhcp server, simply modify inside static lease.

If you want change all lease with specific lease-time (but is effective at the end of current leased time)
simply put for example

/ip dhcp-server lease [find] lease-time=1h

about value, is 4Byte number of seconds, from 0 to 4.294.967.295 seconds, more than 100 years

4

Thanks for reply. So you mean that option 51 (lease time) cannot be set via Option Sets and I HAVE TO use an option in static lease definition?

5

Yes, near all DHCP software ignore “Apple” DHCP 51 request (request for lease bigger than DHCP Server setting)…
If someone set on dhcp server, for example, 1h, 1h must be…

6

Interesting…but clear to me why it does not work. Thanks!