Set DHCP Lease To One Day

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businessuer
businessuer Posts: 134 image  Ally Member
First Comment Friend Collector First Anniversary
in Nebula
Let say person logs in 1 jan at 08:00 hrs and logs out at 1 Jan 17:00 hours.
DHCP Lease set to 2 days.
So will the lease expire at 3 Jan 08:00hrs or 17:00 hrs?

Will setting a lease duration of 1 day be too short because the router have to keep "re-learning" mac addresses? 

Will it affect the hardware? 

Accepted Solution

  • mMontana
    mMontana Posts: 1,443 image  Guru Member
    Zyxel Certified Network Administrator - Security Zyxel Certified Network Administrator - Switch 50 Answers 1000 Comments
    Answer ✓
    businessuer said:

    Will setting a lease duration of 1 day be too short because the router have to keep "re-learning" mac addresses? 

    Will it affect the hardware? 
    Both questions: IMO no.
    In a low-ratio hardware rotation environment (resident people only, two - to five missing person par day on 50-60 persons) having multiple-day lease won't be an issue. If a device come back at the last hours of lease, it will receive the same address.
    In a hi-ratio hardware rotation (bar, restaurant, commercial space, hotel) shorter the lease time, less wasted addresses waiting to expire.

    I choose a /23 subnet for the guests wireless network into an hotel with 60 rooms, considering three devices par room plus 180 devices for congress/dining halls (twice the size of the maximum capacity. Lease time 4 hrs.

All Replies

  • PeterUK
    PeterUK Posts: 4,168 image  Guru Member
    250 Answers 2500 Comments Friend Collector Eighth Anniversary
    edited June 2022

    You can set the Lease time to 2 minutes and it be fine.

    The client can ask for a renew by DHCP by unicast before the lease time and before the client renews by broadcast which reset the lease time.


  • businessuer
    businessuer Posts: 134 image  Ally Member
    First Comment Friend Collector First Anniversary
    Sorry but why is a broadcast necessary?
  • PeterUK
    PeterUK Posts: 4,168 image  Guru Member
    250 Answers 2500 Comments Friend Collector Eighth Anniversary
    edited June 2022
    businessuer said:
    Sorry but why is a broadcast necessary?

    Well you need a broadcast to get a IP but if you mean for renewing a IP the client may not send a unicast request and waits till rebinding which is a broadcast and it can ask for a reply from the server to be a broadcast or unicast.

    More about DHCP here:

    https://lazyadmin.nl/home-network/dhcp-lease-time/


  • mMontana
    mMontana Posts: 1,443 image  Guru Member
    Zyxel Certified Network Administrator - Security Zyxel Certified Network Administrator - Switch 50 Answers 1000 Comments
    Answer ✓
    businessuer said:

    Will setting a lease duration of 1 day be too short because the router have to keep "re-learning" mac addresses? 

    Will it affect the hardware? 
    Both questions: IMO no.
    In a low-ratio hardware rotation environment (resident people only, two - to five missing person par day on 50-60 persons) having multiple-day lease won't be an issue. If a device come back at the last hours of lease, it will receive the same address.
    In a hi-ratio hardware rotation (bar, restaurant, commercial space, hotel) shorter the lease time, less wasted addresses waiting to expire.

    I choose a /23 subnet for the guests wireless network into an hotel with 60 rooms, considering three devices par room plus 180 devices for congress/dining halls (twice the size of the maximum capacity. Lease time 4 hrs.
  • Zyxel_Melen
    Zyxel_Melen Posts: 4,035 image  Guru Member
    Zyxel Certified Network Engineer Level 1 - Switch Zyxel Certified Network Administrator - Switch Zyxel Certified Network Administrator - Nebula Zyxel Certified Sales Associate
    Hi @businessuer,

    Just like @PeterUK's explaination and @mMontana's suggestion, you can depend on your envirement to set suitable lease time, DHCP Server pool and subnet.

    Zyxel Melen


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