A default gateway address and Subnet mask are required for clock configuration. This address can be obtained by running the ipconfig command at a dos prompt.
Click on Start.
Click on Run.
Type CMD
Click OK.
A dos prompt will open.
Type ipconfig and hit enter.
The default gateway and subnet mask are displayed as shown above.
Host Bits According to Subnet Mask
When determining Host Bits for use with an Ethernet connection clock consult the following tables to find your Subnet mask. Use the corresponding number of host bits on your clock. The default Subnet mask in use on most internal networks is 255.255.255.0 with the default host bits setting of 8.
Manually Calculating Host Bits:
To manually calculate the host bits for use with your Subnet mask convert your Subnet mask to binary.
255.255.255.0 Becomes 11111111.11111111.11111111.00000000
Counting the zeroes from right to left, there are eight (8) host bits in the above Subnet mask.
Class A Host/Subnet Table
Host Subnet
Bits Mask
------- ---------------
23 255.128.0.0
22 255.192.0.0
21 255.224.0.0
20 255.240.0.0
19 255.248.0.0
18 255.252.0.0
17 255.254.0.0
16 255.255.0.0
15 255.255.128.0
14 255.255.192.0
13 255.255.224.0
12 255.255.240.0
11 255.255.248.0
10 255.255.252.0
9 255.255.254.0
8 255.255.255.0
7 255.255.255.128
6 255.255.255.192
5 255.255.255.224
4 255.255.255.240
3 255.255.255.248
2 255.255.255.252
1 255.255.255.254
Class B Host/Subnet Table
Host Subnet
Bits Mask
------- -----------------
15 255.255.128.0
14 255.255.192.0
13 255.255.224.0
12 255.255.240.0
11 255.255.248.0
10 255.255.252.0
9 255.255.254.0
8 255.255.255.0
7 255.255.255.128
6 255.255.255.192
5 255.255.255.224
4 255.255.255.240
3 255.255.255.248
2 255.255.255.252
1 255.255.255.254
Class C Host/Subnet Table
Host Subnet
Bits Mask
------- ---------------
7 255.255.255.128
6 255.255.255.192
5 255.255.255.224
4 255.255.255.240
3 255.255.255.248
2 255.255.255.252
1 255.255.255.254