Just like many addresses we’ve talked about in our previous articles, 192.168.1.128 is also a private IP address from the block of private addresses within class C. Unlike all the other addresses we’ve talked about, this one is not used as a default gateway by router manufacturers unless you decide to assign it manually to a router (which is absolutely possible). Just like any other private IP address, this one can be assigned to a client within a home or a corporate network (it can be static or dynamic) or it can be the IP address reserved for a subnetwork if you decide to split a larger scope of available IP addresses (let’s say a scope from 192.168.1.1 to 192.168.1.254) into two smaller scopes (first – from 192.168.1.1 to 192.168.126 and second – from 192.168.1.129 to 192.168.1.254).
192.168.1.128 as A Host IP address (Static or Dynamic)
If you are using some 192.168.1.1 router (the majority of home routers use this address as a default gateway), 192.168.1.128 will probably be one of the available addresses in DHCP pool (in case this pool has 254 available addresses). DHCP server inside your router assigns IP addresses sequentially (the first device that gets connected to the network gets 192.168.1.2 IP address, the second gets 192.168.1.3, etc.). 192.168.1.128 will be available but the chance of getting it assigned to some of your devices dynamically (automatically) by the DHCP server is almost non-existent (unless you have 127 different devices connected to your router).
You can always assign this address manually to some of your devices. Printers usually have static IPs but you can assign a static IP to any of your devices by making a reservation in DHCP pool. 192.168.1.128 can be considered a safe choice for a static IP (especially for home networks) since there is practically no chance of having 127 devices connected to a home router at the same time. If you assign this address manually to some device, the possibility of an IP conflict will be minimal.
192.168.1.128 as A Network (or Subnetwork) Address
If you don’t need a large network made of 254 IP addresses, or if you need two separated subnetworks for some reason, you can always split a large network (for example 192.168.1.1-192.168.1.254 with a network ID 192.168.1.0 and a broadcast address 192.168.1.255) into two smaller ones:
First: 192.168.1.1 – 192.168.1.126 (with a (sub)network address 192.168.1.0 and a broadcast address 192.168.1.127)
Second: 192.168.1.129 – 192.168.1.254 (with a (sub)network address 192.168.1.128 and a broadcast address 192.168.1.255)
In order to understand how this split is done, you need to have some basic understanding of subnetting and subnet masks – we recommend reading two of our previous articles – 192.168.1.1 (Default Gateway) and 192.168.1.0 (Network ID).
A subnet mask is a tool that divides an IP address into two parts – the first referring to the network (or subnetwork) and the second referring to the host. In order to route a packet to the right client, your router has to process every IP address in a specific manner. It separates the IP address of the specific destination client into two parts by using the subnet mask. After reading the first part of the address (the (sub)network part), your router determines the (sub)network where the destination client is located, and after reading the second part (the host part), it determines the exact destination host (client).
192.168.1.128 will be one of the (sub)network IDs if you decide to make four subnetworks (62 clients within each subnetwork) – this address will be the (sub)network ID for a scope 192.168.1.129 – 192.168.1.190.
If you decide to make 8 subnetworks with 30 IP addresses (clients) within each subnetwork this IP address will be the (sub)network ID for a scope 192.168.1.129 – 192.168.1.158, etc.
You can make up to 64 subnetworks (each with 2 clients) and 192.168.1.128 will always be one of the (sub)network IDs.