Which candidate is a syntactically valid Internet Protocol version 4 (IPv4) address?

### Why this is right An IPv4 address has four decimal octets separated by periods. Each octet must be in the range 0 through 255, so `10.1.2.3` meets both requirements. ### The concept An octet is an eight-bit part of an IPv4 address. Eight bits can represent values from 0 to 255. A valid-looking address must have exactly four octets and use the expected dotted-decimal format. Passing this syntax check does not prove that an address is assigned to a device or that it is reachable. ### The other options - **B. 192.168.73.279**: The last octet is greater than 255. It is tempting because the address has four dotted numbers, but one number is out of range. - **C. 10.9.222**: It has only three octets. IPv4 requires four. - **D. 192:168:3:5**: The separators are colons rather than periods. Colons are associated with IPv6 notation, not the IPv4 format shown here. ### Terms - **IPv4**: Internet Protocol version 4. The 32-bit addressing system written as four decimal octets. - **Octet**: An eight-bit group, written as one decimal number from 0 to 255. - **IPv6**: Internet Protocol version 6. A newer addressing system that uses longer addresses, commonly written with hexadecimal groups. ### Remember Check the address has four period-separated numbers, and that every number is between 0 and 255.