Select the name of the network interface where this DHCP server will listen for requests from DHCP clients.

Type the IP address that DHCP clients will use as their next-hop router.

On smaller networks, this is usually the same router that FortiRecorder uses. It could be your office’s router, or cable/DSL modem.

Select either:

Type the IP address of a DNS server that DHCP clients can use to resolve domain names. For performance reasons, if you have one, it is preferable to use a DNS server on your local network.

This setting is available only if DNS options is set to Specify.

Type the IP address of an alternative DNS server that DHCP clients can use to resolve domain names. For performance reasons, if you have one, it is preferable to use a DNS server on your local network.

This setting is available only if DNS options is set to Specify.

Optional. Type the domain name, if any, that DHCP clients will use when resolving host names on the local domain.

Type the subnet mask that DHCP clients will use in conjunction with the IP address that is assigned by FortiRecorder’s DHCP server.

Type the maximum amount of time that the DHCP server will wait for an ICMP ECHO (ping) response from an IP before it determines that it is not used, and therefore safe to allocate to a DHCP client that is requesting an IP address. The default is 1,800 seconds (3 minutes).

To ensure that the DHCP server does not cause IP address conflicts with misconfigured computers that are accidentally using the pool of IP addresses used for DHCP, when a client request a new DHCP lease, the built-in DHCP server will ping an unused IP address in the pool first. If the ping test is successful, then a misconfigured computer is currently using that IP, and allocating it also to the DHCP client would cause an IP address conflict. To prevent this, the DHCP server will temporarily abandon that IP (mark it as used by a static host) and look for an other, available IP to give to the DHCP client. (It will not try abandoned IPs again until the pool is exhausted.) However, before the DHCP server can determine if the ping test is successful, the it must first wait to see if there is any reply. This slows down the search for an available IP address, and in rare cases, could cause a significant delay before the DHCP client receives its assigned IP address and other network settings. If your network is smaller or typically has low latency to ping replies, you can safely decrease this setting’s value to improve DHCP speed and performance. In most cases, 3 seconds is enough.

Type the maximum amount of time that the DHCP client can use the IP address assigned to it by the server. When the lease expires, the DHCP client must either request a new IP address from the DHCP server or renew its existing lease. Otherwise, the DHCP server may attempt to assign it to the next DHCP client that requests an IP. The default is 604,800 seconds (7 days).

If you have more or almost as many DHCP clients (cameras) as the number of IP addresses available to give to DHCP clients, you can decrease the lease. This will free up IP addresses from inactive clients so that IPs are available to give to clients that are currently in need of IP addresses. Keep in mind, however, that if the DHCP server is attached to your overall network rather than directly to cameras, this will slightly increase traffic volume and slightly decrease performance.

To configure the DHCP lease pool — the range of IP addresses that the DHCP server can assign to its clients — click New and configure the first and last IP address in the range. To avoid DHCP pool exhaustion that can occur in some cases, the pool should be slightly larger than the total number of clients.

If you need to exclude some IP addresses from this range (e.g. printers permanently occupy static IPs in the middle of the range), also configure DHCP Excluded Range.

Tip: The built-in DHCP server can provide IP addresses to the computers on your network too, not just to cameras.

To configure IPs that should be omitted from the DHCP pool and never given to DHCP clients (such if there are printers with manually assigned static IP addresses in the middle of your DHCP range), click New.

To bind specific MAC addresses to a specific DHCP lease, guaranteeing that the DHCP server will never assign it to another DHCP client, click New.

Caution: Reserved leases cannot prevent misconfigured computers from taking the IP address, causing an IP address conflict, and breaking the FortiRecorder NVR’s connection with the camera. See “Resolving IP address conflicts”.

Tip: To mimic a static IP address for your cameras, yet still provide the benefit that IP addresses are still centrally managed and configured on your DHCP server, configure reserved IP addresses.