Networking Fundamentals
IP, TCP, DNS and the layers underneath every request.
Backend Engineer track
Junior
Write correct code, ship small changes safely, ask good questions.
Core: start here
- DNSThe internet's phone book, turning names into IP addresses.
- IP AddressA numeric address identifying a device on a network.
- PortA number identifying a specific service on a host.
4 more junior concepts
- Domain NameA human-readable address like example.com.
- Latency vs BandwidthHow long data takes to arrive vs how much can flow at once.
- localhost / 127.0.0.1The address that always means "this machine".
- ping and tracerouteChecking reachability and the path packets take.
Mid-level
Own a feature end to end without hand-holding.
- Connect Timeout vs Read TimeoutWaiting to establish a connection vs waiting for data on it.
- Connection PoolingReusing a set of open connections instead of opening new ones.
- DHCPHow devices get an IP address automatically when they join a network.
- DNS Record TypesA, AAAA, CNAME, MX, TXT, NS and what each one does.
- DNS TTL and PropagationHow long DNS answers are cached, and why changes take time to spread.
- FirewallRules that allow or block network traffic.
- FTP and SFTPOlder file transfer protocols, and the SSH-based secure version.
- ICMPThe protocol behind ping and many network error messages.
- Inspecting Connections (ss, netstat, lsof)Seeing which ports and connections a machine has open.
- IPv4 vs IPv632-bit vs 128-bit addresses, and why IPv6 exists.
- Keep-Alive ConnectionsReusing one connection for many requests.
- NATMany private addresses sharing one public IP.
- OSI ModelA seven-layer model of how network communication is structured.
- PacketA unit of data sent over a network.
- Private IP RangesAddress blocks reserved for internal networks.
- Round-Trip Time (RTT)The time for a message to go out and a reply to come back.
- SocketAn endpoint for sending and receiving data over a network.
- Subnet and CIDRDividing IP ranges, written like 10.0.0.0/16.
- TCPReliable, ordered, connection-based transport.
- TCP Three-Way HandshakeSYN, SYN-ACK, ACK: how a TCP connection starts.
- TCP/IP ModelThe practical four-layer model the internet actually runs on.
- ThroughputHow much work or data gets through per unit of time.
- UDPFast, connectionless transport with no delivery guarantees.
- VPNAn encrypted tunnel into another network.
Senior
Own a system, its failure modes, and its trade-offs.
- AnycastOne IP address served from many locations, sending users to the nearest.
- ARPFinding the hardware address behind an IP on a local network.
- Head-of-Line BlockingOne slow item holding up everything queued behind it.
- MTUThe largest packet size a network link can carry.
- Network PartitionPart of a network becoming unreachable from the rest.
- Packet Capture (tcpdump, Wireshark)Recording and inspecting raw network traffic.
- QUICA UDP-based transport behind HTTP/3, with faster handshakes.
- RoutingHow packets find their way across networks.
Staff
Shape how many teams build, across systems.
Nothing here yet.
Principal
Set technical direction for the organization.
- BGPThe protocol that routes traffic between the internet's networks.
Data Engineer track
Junior
Build and fix pipelines from clear specs; write correct SQL.
- DNSThe internet's phone book, turning names into IP addresses.
- Domain NameA human-readable address like example.com.
- IP AddressA numeric address identifying a device on a network.
- Latency vs BandwidthHow long data takes to arrive vs how much can flow at once.
- localhost / 127.0.0.1The address that always means "this machine".
- ping and tracerouteChecking reachability and the path packets take.
- PortA number identifying a specific service on a host.
Mid-level
Own pipelines and models end to end, including their quality.
- Connect Timeout vs Read TimeoutWaiting to establish a connection vs waiting for data on it.
- Connection PoolingReusing a set of open connections instead of opening new ones.
- DHCPHow devices get an IP address automatically when they join a network.
- DNS Record TypesA, AAAA, CNAME, MX, TXT, NS and what each one does.
- DNS TTL and PropagationHow long DNS answers are cached, and why changes take time to spread.
- FirewallRules that allow or block network traffic.
- FTP and SFTPOlder file transfer protocols, and the SSH-based secure version.
- ICMPThe protocol behind ping and many network error messages.
- Inspecting Connections (ss, netstat, lsof)Seeing which ports and connections a machine has open.
- IPv4 vs IPv632-bit vs 128-bit addresses, and why IPv6 exists.
- Keep-Alive ConnectionsReusing one connection for many requests.
- NATMany private addresses sharing one public IP.
- OSI ModelA seven-layer model of how network communication is structured.
- PacketA unit of data sent over a network.
- Private IP RangesAddress blocks reserved for internal networks.
- Round-Trip Time (RTT)The time for a message to go out and a reply to come back.
- SocketAn endpoint for sending and receiving data over a network.
- Subnet and CIDRDividing IP ranges, written like 10.0.0.0/16.
- TCPReliable, ordered, connection-based transport.
- TCP Three-Way HandshakeSYN, SYN-ACK, ACK: how a TCP connection starts.
- TCP/IP ModelThe practical four-layer model the internet actually runs on.
- ThroughputHow much work or data gets through per unit of time.
- UDPFast, connectionless transport with no delivery guarantees.
- VPNAn encrypted tunnel into another network.
Senior
Design the platform's storage, processing and modeling choices.
- Head-of-Line BlockingOne slow item holding up everything queued behind it.
- Network PartitionPart of a network becoming unreachable from the rest.
- Packet Capture (tcpdump, Wireshark)Recording and inspecting raw network traffic.
- QUICA UDP-based transport behind HTTP/3, with faster handshakes.
- RoutingHow packets find their way across networks.
Staff
Shape how the whole organization produces and uses data.
Nothing here yet.
Principal
Set data strategy and architecture across the company.
Nothing here yet.
Frontend Engineer track
Junior
Build UI that works, ship small changes safely, ask good questions.
- DNSThe internet's phone book, turning names into IP addresses.
- Domain NameA human-readable address like example.com.
- IP AddressA numeric address identifying a device on a network.
- Latency vs BandwidthHow long data takes to arrive vs how much can flow at once.
- localhost / 127.0.0.1The address that always means "this machine".
- PortA number identifying a specific service on a host.
Mid-level
Own a feature end to end without hand-holding.
- Connect Timeout vs Read TimeoutWaiting to establish a connection vs waiting for data on it.
- DNS Record TypesA, AAAA, CNAME, MX, TXT, NS and what each one does.
- DNS TTL and PropagationHow long DNS answers are cached, and why changes take time to spread.
- FirewallRules that allow or block network traffic.
- IPv4 vs IPv632-bit vs 128-bit addresses, and why IPv6 exists.
- Keep-Alive ConnectionsReusing one connection for many requests.
- OSI ModelA seven-layer model of how network communication is structured.
- PacketA unit of data sent over a network.
- Round-Trip Time (RTT)The time for a message to go out and a reply to come back.
- SocketAn endpoint for sending and receiving data over a network.
- TCPReliable, ordered, connection-based transport.
- TCP Three-Way HandshakeSYN, SYN-ACK, ACK: how a TCP connection starts.
- TCP/IP ModelThe practical four-layer model the internet actually runs on.
- ThroughputHow much work or data gets through per unit of time.
- UDPFast, connectionless transport with no delivery guarantees.
- VPNAn encrypted tunnel into another network.
Senior
Own an app's architecture, performance, and failure modes.
- Head-of-Line BlockingOne slow item holding up everything queued behind it.
- QUICA UDP-based transport behind HTTP/3, with faster handshakes.
Staff
Shape how many teams build, across apps.
Nothing here yet.
Principal
Set technical direction for the organization.
Nothing here yet.