title: DHCP lease checkup
body: <p>I'm currently developing an Embedded device, which uses TCP-IP, and get's it's IP address with DHCP.
  I saw in examples, that every now and then, I need to check if the lease has ended, but I didn't find any reference about how often to check it, because there are implementation who check it once in 8 days, and implementation which check it every 24 hours.
  so basically, in your implementations, How often do you check the DHCP lease ? what's the standard regarding this issue ?</p>