Understand how IPv4 addressing works. IP addresses are 32-bit addresses written as four octets in dotted-decimal notation, such as 192.168.5.18. To communicate on an IP network, a host also needs a subnet mask, which may look something like 255.255.255.0.

Understand how IPv6 addressing works. IPv6 addresses are 128-bit addresses written as eight fields of four hexadecimal characters, such as 2001:0db8:3c4d:0012:0000:0000:1234:56ab. Using shorthand conventions, this address can also be written as 2001:db8:3c4d:12::1234:56ab.

Know what DHCP and DNS do. On TCP/IP networks, the DHCP server can provide IP configuration information to hosts. A DNS server resolves hostnames to IP addresses.

Know common TCP/IP ports. Some common protocol and port pairings you should know are HTTP (80), FTP (20 and 21), POP3 (110), SMTP (25), Telnet (23), and HTTPS (443).

Be able to identify IP address classes. Know how to identify Class A, B, and C IP addresses. Class A addresses will have a first octet in the 1 to 126 range. B is from 128 to 191, and C is from 192 to 223.

Know what the private IP addresses ranges are. Private IP addresses will be in one of three ranges: 10.0.0.0/8, 172.16.0.0/16, or 192.168.0.0/16.

Know what the APIPA range is. IP addresses in the 169.254.0.0/16 range are APIPA addresses.