The IP addresses you have been given break down as follows.
221.62.135.170
– network (reserved but this tells you the identity of the network)
221.62.135.171 – router Ethernet ip -(this is basically your gateway address and is used for accessing other networks)
221.62.135.172-176 LAN ips -( This will be the address range you have been given for the PC’s are you network i.e. 172, 173, 174,175 and 176)
221.62.135.177 – Broadcast (used for PC’s to talk with each other (I think).
255.255.255.248 (This is used to break 221.62.135.0-255 up into several networks).
Saying all that none of the above numbers really gel together they are in different subnets/networks.