@keefeglise

To make it *actually* static, either the DHCP server has to be explicitly told that network card A always gets a lease for IP address P when it asks, or the machine with network card A has to be told to not use DHCP at all and to instead always use IP address Q.

In the latter case, there are anti-collision mechanisms, but in theory the DHCP server can lease another machine IP address Q, causing a conflict, *unless* that address is outwith the range of IP addresses that the DHCP server will hand out leases for.

So if the DHCP-leasable IP address range is (say) 192.168.1.100 to 192.168.1.253, address Q would have to be somewhere in the range 192.168.1.2 to 192.168.1.99. (Simple example. Real world can get more complex. May contain traces of nuts.)

@stroz @dzwiedziu @gavin57
#LAN #NetworkAdministration #DHCP

@keefeglise

To contrast how it's done with routers that have this capability, here's a mock-up that #TPLink provides for its router administration UI. (I've picked a domestic router model at random.)

https://emulator.tp-link.com/TL-WR843ND/Index.htm

Under DHCP→Address Reservation on the menu on the left-hand side, you can see where the router presents the capability to enter a NAS machine's MAC address and have it always assign a specific fixed IP address for that MAC address.

The 'hubs' that one gets from cable/ADSL companies are often bare minima, functionality-wise. Which is why the cool LAN admin kids always talk of having their hubs in 'pass-through' or 'modem' mode and using their own, better, kit for DHCP and whatnot.

@stroz @dzwiedziu @gavin57
#DHCP #LAN #NetworkAdministration

@zrail

Yes. After doing it once one always has the lurking suspicion that one day one will come up against the LAN of someone else who has had the very same idea — whose birthday, or lucky numbers, or CRC16, or whatever just happen to make the same octets in the network part.

Then there are things like having an ISP that uses various parts of 10.0/8 for its internal infrastructure. Even my own ISP uses 192.168.100.0/24 for its own purposes on customer-premises equipment.

@mdavis
#RFC1918 #IPv6 #IPv4 #SiteLocalAddresses #PrivateUseAddresses #LANs #NetworkAdministration