What can be done to reduce IP address wastage in Image $1?$Blank $1$

Which interface represents the gateway for PC$1$ in Image $1?$Blank $2$

Which interface represents the gateway for PC$8$ in Image $1?$Blank $3$

Which interface represents the gateway for DHCP Server in Image $1?$Blank $4$

Which interface represents the gateway for Router A in Image $1?$Blank $5$

Which interface represents the gateway for Router B in Image $1?$Blank $6$