To provide Internet connectivity to homes, ISPs often provide a gateway device to their customers. By connecting a router to the gateway, users create their own local network. A gateway used to be a layer-2 device that extends WAN into an individual's home, but it now provides routing functionality built into the gateway so the term is loosely used.

A DMZ (Demilitarized Zone) is a network (or a node) used to connect internal resources to the untrusted outside world, usually the Internet. By creating a separate "danger" zone, internal resources are within the private network are not directly accessible from the outside world. In traditional corporate networks, the servers providing services to the outside world such as the webserver, email server, and DNS server are isolated inside the DMZ network so that the internal network is protected even if DMZ is compromised. With the explosive growth in cloud networks, the majority of public servers are relocated to cloud servers and there is less demand for DMZ than before. However, there are still some gateway servers providing access to the internal resources that are confined within the DMZ network.

Burte force attack is a method used to guess username and password combination continuously until the valid login is discovered. Hackers use password cracking software to guess all possible passwords for a known username to gain access to the target system.

The YubiKey is a hardware device that generates passcodes for 2-factor authentication (2FA). It is not a password manager and does not store username/password pairs for your online accounts. It is a pure 2FA device that generates HMAC-based One Time Passwords (HOTP) and Time-based One Time Passwords (TOTP) that you can plug (or NFC) into your smart device. The YubiKey is recognized as a human interface device (HID) and delivers password as if the keystrokes are coming from a keyboard.

Microsoft lagging behind Google and Apple on browser war, and also fell behind on the password manager debut. Microsoft finally completed its password manager beta testing, and officially released Autofill password manager that utilizes Microsoft Authenticator. This is good news for Edge users, but Chrome users on the Mac, Windows, iOS, and Android can also benefit from it. We all know creating strong passwords for online accounts is a hassle, and remembering them is even worse. More free tools like Autofill will help online users from steering away from using weak passwords and reusing the same password for multiple accounts.

Google password manager is built into the Chrome web browser, and it interacts with the web forms automatically if you're using the Chrome browser. The first time you submit a login form, the Chrome browser will prompt if you want to store the username and password pair in a vault on your computer, and whether you want to sync them to the cloud on your Google account. The next time you visit the same site, once you enter the username portion of the form Google Chrome will auto-populate the password field. If you sync your passwords with your Google account, all the passwords are available on every device you use as long as you use Google Chrome and sign onto your Google account.

A local area network (LAN) is a group of smart devices connected together to create a network within the same location. A home is a good example of LAN consisting of a few computers, tablets, smartphones and IoTs devices over the physical wires and through the Wi-Fi. A LAN can be as small as connecting 2 devices or as large as enerprise network interconnecting thousands of computers, servers and smart devices. A few other examples of LAN include offices, buildings, schools, and corporations.

Both TCP and UDP are protocols used to send data from one device to anoter within the TCP/IP network. When sending data, they are broken into smaller IP packets and sent over the TCP or UDP transport layer. Applications may choose to use either TCP or UDP to send data to the other end depending on whether the reliability or speed is more important. For reliable delivery, TCP is used while UDP is used for faster delivery. TCP/IP is comprised of 4 layers with each providing a specific protocol functions as shown below:

An Autonomous System (AS) is a large network that has a common routing policy used to serve a set of IP prefixes. An AS is assigned to a single organization and is connected to multiple ASes to route IP packets in a redundant manner. An AS is assigned a 16-bit or 32-bit number (ASN) by the IANA to Internet Service Providers (ISPs), governments, universities, and enterprises.

A RIR (or Regional Internet Registry) is a nonprofit organization that allocates Internet Numbers which is comprised of IPv4 Addresses, IPv6 Addresses, and ASN (Autonomous System Numbers) within their respective regions. An IP address is a globally unique number that is assigned to computing devices to communicate with each other within a network (or Internet). ASN is a group of one or more IP prefixes that are used to define routing policy. With IP Address and ASN, IP packets are routed from one IP address to another regardless of where they are located within the world. There are 5 RIRs in the world, and their serving regions: