Book 11
Networking
How data travels between machines: addresses, ports, protocols and the things that make connections fast, slow or safe.
Contents
- 01ARPAddress Resolution Protocol1ARP is a network protocol that finds the MAC address belonging to an IPv4 address on the local network, so a device knows where to deliver each Ethernet frame.
- 02Bandwidth2Bandwidth is the maximum amount of data a network connection can carry per second, usually measured in megabits or gigabits per second (Mbps or Gbps).
- 03BGPBorder Gateway Protocol3BGP (Border Gateway Protocol) is the routing protocol that links the internet's autonomous systems by letting them announce which IP ranges they can reach.
- 04CIDRClassless Inter-Domain Routing4CIDR (Classless Inter-Domain Routing) writes an IP range as an address and prefix length, like 10.0.0.0/16; the prefix counts the leading network bits.
- 05Default Gateway5A default gateway is the router a device sends traffic to whenever the destination lies outside its own subnet, acting as the network's exit to other networks.
- 06DHCPDynamic Host Configuration Protocol6DHCP is a network protocol that automatically gives devices an IP address and other settings, such as the router and DNS server, when they join a network.
- 07DNS Record7A DNS record is an entry in a domain's DNS zone that maps a name to information, such as an IP address (A, AAAA), another name (CNAME) or mail servers (MX).
- 08Firewall8A firewall is a security system that checks network traffic and allows or blocks it based on rules, acting as a barrier between trusted and untrusted networks.
- 09HTTP/29HTTP/2 is the second major version of HTTP, sending many requests and responses at once over one connection in a compact binary format so pages load faster.
- 10HTTP/310HTTP/3 is the third major version of HTTP, which runs over the QUIC protocol on UDP instead of TCP to load pages faster, especially on unreliable networks.
- 11IP AddressInternet Protocol Address11An IP address is a numeric label assigned to each device on a network so that data can be routed to it, much like a postal address for a house.
- 12IPv4Internet Protocol version 412IPv4 is the internet's original addressing system, using 32-bit addresses written as four numbers such as 192.168.1.10, allowing about 4.3 billion addresses.
- 13IPv6Internet Protocol version 613IPv6 is the newest version of the Internet Protocol, using 128-bit addresses that give every device a unique address and replace the exhausted IPv4 pool.
- 14LANLocal Area Network14A LAN is a network that connects devices within a small area such as a home, office or school, letting them reach each other directly and share resources fast.
- 15Latency15Latency is the delay between sending a request and the start of a response, usually measured in milliseconds, and it shapes how responsive an app feels.
- 16Localhost16Localhost is the hostname for the computer you are using; it resolves to the loopback address 127.0.0.1 (::1 in IPv6), so its traffic stays on the machine.
- 17MAC AddressMedia Access Control Address17A MAC address is a 48-bit hardware identifier assigned to a network interface and used to deliver data between devices on the same local network.
- 18NATNetwork Address Translation18NAT is a technique in which a router rewrites the IP addresses in passing packets, letting many devices on a private network share one public IP address.
- 19Network Switch19A network switch is a device that connects devices on the same local network and forwards each frame only to the port where its destination MAC address lives.
- 20OSI ModelOpen Systems Interconnection Model20The OSI model is a conceptual framework that splits network communication into seven layers, from physical cables up to the applications people use.
- 21Packet21A packet is a small, formatted unit of data sent across a network, made of a header with addressing information and a payload that carries the actual data.
- 22Ping22Ping is a network utility that checks whether a host is reachable by sending it small ICMP echo requests and measuring how long each reply takes to return.
- 23Port23A port is a number from 0 to 65535 that identifies a specific program or service on a device, so traffic reaching an IP address gets to the right application.
- 24Proxy Server24A proxy server is an intermediary that receives network requests on behalf of clients or servers and passes them on, adding control, caching, or privacy.
- 25QUIC25QUIC is a modern transport protocol built on UDP that provides encrypted, reliable, multiplexed connections with fast setup, and it is the foundation of HTTP/3.
- 26Router26A router is a networking device that forwards packets between different networks, choosing the next hop for each one based on its destination IP address.
- 27SFTPSSH File Transfer Protocol27SFTP (SSH File Transfer Protocol) is a protocol for securely uploading, downloading and managing files on a remote server over an encrypted SSH connection.
- 28SMTPSimple Mail Transfer Protocol28SMTP is the internet's standard protocol for sending email, used by apps to submit messages and by mail servers to relay them to the recipient's mail server.
- 29Socket29A socket is a software endpoint that a program opens to send and receive data over a network, identified by an IP address, a port number, and a protocol.
- 30SSHSecure Shell30SSH is a cryptographic network protocol for securely logging in to and running commands on remote computers, encrypting all traffic between the two machines.
- 31Subnet31A subnet is a smaller network carved out of a larger one by splitting its range of IP addresses, which keeps traffic organized, contained, and easier to secure.
- 32TCPTransmission Control Protocol32TCP is a core internet protocol that delivers data between two programs reliably and in order, by opening a connection and resending anything that gets lost.
- 33TCP Handshake33The TCP handshake is the SYN, SYN-ACK, ACK exchange a client and server use to open a connection and agree on starting sequence numbers before sending data.
- 34Throughput34Throughput is the amount of data or work a system actually handles per unit of time, like megabits per second on a network or requests per second on a server.
- 35Traceroute35Traceroute is a network diagnostic tool that lists every router a packet passes through on its way to a destination, along with the delay to reach each one.
- 36TTLTime to Live36TTL (time to live) is a limit on how long data stays valid: router hops left for an IP packet, or seconds a DNS or cached answer may be reused.
- 37UDPUser Datagram Protocol37UDP is a lightweight internet protocol that sends small, independent messages called datagrams without a connection, favoring speed over guaranteed delivery.
- 38VPNVirtual Private Network38A VPN is a technology that creates an encrypted tunnel between a device and another network, so traffic can travel privately across the public internet.
- 39WANWide Area Network39A WAN is a network that connects devices and local networks across large distances, such as cities or countries, often over links rented from telecom providers.