nput Validation: Regular Expression

What is the regular expression pattern to check if an IP address is within the range $192\mathrm{.}168\mathrm{.}1\mathrm{.}0$ to $192\mathrm{.}168\mathrm{.}1\mathrm{.}255?$

Write a pattern that can match an Purchase Order Number PO$-$kean$-$yyyy or PO#kean$-$xxxx or PO kean$-$yyyy in a sale, where x is a number from $0$ to $9$ and y is a letter from A to Z or a to z$.$