How systems reach each other
Networking
Addressing, routing, switching, name resolution, segmentation, remote access and the protocols that carry enterprise traffic.
Protocols
ARP
Address Resolution Protocol maps IPv4 addresses to MAC addresses within a local broadcast domain.
ReadDHCP
Dynamic Host Configuration Protocol automatically issues IP addresses and network configuration to clients as they join a network.
ReadDNS
The Domain Name System is the distributed, hierarchical directory that resolves names to addresses and service records for nearly every other service.
ReadHTTP & HTTPS
The request/response protocol of the web, and its TLS protected form, which now carries most enterprise application traffic.
ReadICMP
The control and diagnostic protocol of IP, carrying echo requests, unreachable messages and fragmentation needed signalling.
ReadNTP
Network Time Protocol synchronises clocks across an estate, which is a prerequisite for authentication, logging and forensics.
ReadSMB
Server Message Block is the Windows file and printer sharing protocol, operating over TCP/445 in modern deployments.
ReadSNMP
Simple Network Management Protocol collects counters and state from network devices and sends traps on events.
ReadSSH
Secure Shell provides encrypted remote administration, file transfer and tunnelling, usually on TCP/22.
ReadTLS
Transport Layer Security provides confidentiality, integrity and server authentication for application traffic, most visibly as HTTPS.
ReadRouting & Switching
BGP
The path vector protocol that exchanges reachability between autonomous systems and, increasingly, inside data centre fabrics.
ReadOSPF
A link state interior gateway protocol that floods topology information within areas and computes shortest paths using Dijkstra's algorithm.
ReadRouting
Forwarding packets between networks by selecting the best available path from a route table.
ReadSwitching
Layer 2 forwarding of frames within a broadcast domain using learned MAC address tables.
ReadEdge & Perimeter
CDN
Content delivery networks cache and serve content from distributed edge locations, improving latency and absorbing volumetric attack traffic.
ReadFirewalls
Policy enforcement points that permit or deny traffic between network zones based on connection state, identity and application context.
ReadLoad Balancing
Distributing client requests across multiple backend servers to provide scale, resilience and maintainability.
ReadProxies & Reverse Proxies
Intermediaries that terminate and re originate connections, enabling inspection, caching, publishing and policy enforcement.
ReadFundamentals
IPv6
The 128 bit successor to IPv4, with vastly larger address space, mandatory multicast based neighbour discovery and no need for NAT.
ReadNAT
Network Address Translation rewrites addresses and ports in transit, most commonly to share public addresses among many private hosts.
ReadOSI Model
A seven layer conceptual model that separates network communication into distinct, independently replaceable functions.
ReadSubnetting & CIDR
Dividing IP address space into right sized networks using prefix length notation, so that routing, segmentation and growth all remain manageable.
ReadTCP/IP
The protocol suite that actually runs the internet and virtually every enterprise network, organised into link, internet, transport and application layers.
ReadSegmentation
Remote Access
RDP
Remote Desktop Protocol delivers interactive Windows sessions over TCP/3389 and is a recurring ransomware entry point when exposed.
ReadSD-WAN
Software defined WAN overlays that steer application traffic across multiple transports using centrally managed policy.
ReadVPN
A virtual private network carries private traffic across untrusted networks inside an authenticated, encrypted tunnel.
Read