How to determine whether a client falls in the subnet range of the Group Update Provider (GUP) client IP?
While designating a computer as a GUP, it is important to understand your organization’s IP addressing scheme. Often this information can be obtained from the network team.
Once you have the subnet information, select a client (or an IP address from that range) to be designated as the GUP.
Note: If you are using DHCP for assigning IP addresses to clients it is recommended that you assign a static IP address to the GUP client and excluding it from DHCP.
How to determine whether a client falls in the subnet range of the GUP client IP?
Consider the below example.
Consider two clients and one GUP.
ClientA => IP: 172.16.0.42 Subnet Mask: 255.255.255.240
ClientB => IP: 172.16.0.10 Subnet Mask: 255.255.255.240
GUP Client => ClientA => IP: 172.16.0.14 Subnet Mask: 255.255.255.240
These are Class B IP addresses.
Refer the highlighted section of 'Subnetting IP Addresses' below. The subnet mask 255.255.255.240 gives you 4096 subnets with 14 hosts per subnet (Excluding the network IP and broadcast IP)
Finding out the IP address ranges for the subnets.
Now refer the highlighted section of the 'Subnets' section.
The various subnets are-
172.16.0.0 to 172.16.0.15
172.16.0.16 to 172.16.0.31
172.16.0.32 to 172.16.0.47
172.16.0.240 to 172.16.0.255
In the above example ClientB will get the updates from GUP however Client A will not get updates from the GUP.
ClientB and GUP client fall in the same subnet range 172.31.1.0 to 172.31.1.15.
ClientA's subnet range is 172.16.0.32 to 172.16.0.47.