A technician is troubleshooting a customer's network connectivity issue. He needs to determine the IP address of the customer's router. The customer has an IP address of $192\mathrm{.}168\mathrm{.}1\mathrm{.}55/24.$ Which of these is the address of the customer's router?

A $192\mathrm{.}168\mathrm{.}0\mathrm{.}5$

B $192\mathrm{.}168\mathrm{.}1\mathrm{.}1$

C $192\mathrm{.}168\mathrm{.}5\mathrm{.}55$

D $192\mathrm{.}168\mathrm{.}100\mathrm{.}1$