Computer Networking Masterclass: Interview Success

Explore layer two switches and mac addresses, including how switches forward data using mac addresses, vlans, quality of service, and port mirroring to improve lan performance and security.

Learn how arp maps an ip address to a mac address on the same network, builds arp tables, and uses broadcast requests and replies to resolve addresses.

Master switchport modes such as access, trunk, dynamic auto, dynamic desirable, VLAN only, and general mode. Learn how VLAN tagging enables multiple VLANs on trunk ports.

Understand layer three switches that combine switching and routing to move traffic between subnets, operate at layer two and layer three, support ACLs, QoS, and OSPF/BGP in enterprises, reducing costs.

Routing moves data between different networks using IP, BGP, and OSPF to determine the best path, while switching moves data within a network or VLAN using MAC addresses.

Explore OSPF area types, including backbone area and stub areas, and how ABRs generate default routes and stub router LSAs to limit external LSAs.

Explore BGP message types—open, update, notification, keepalive, and router refresh—and learn key attributes like S path, next hop, origin, local preference, med, and community that guide path selection.

Explore how BGP routers exchange routes through peering over TCP port 179 and use update messages, open messages, and keepalive to advertise or withdraw routes and select the best path.

Set the maximum transmission unit, the largest packet size without fragmentation, for each network. Use jumbo frames where supported and path MTU discovery to prevent VPN connectivity issues.

Explore how tcp ensures reliable, ordered, connection-oriented delivery over ip networks, highlighting header fields such as source and destination ports, sequence and acknowledgement numbers, and window size.

Learn how tcp terminates connections with a four-way handshake to gracefully close using a fin exchange, and contrast it with an abrupt termination via a tcp reset packet.

Explore how UDP operates as a connectionless, unreliable transport with a four-field header and independent datagrams. Its low overhead supports real-time use like streaming and online gaming.

Discover port numbers for common services, such as http/https on 80 and 443 and ftp on 21/20, along with dns 53 and dhcp 67/68.

Compare M2 and RMS to grasp how the maximum packet size and TCP payload vary across data link, network, and transport layers, including fragmentation and the TCP handshake.

Explore how the http protocol enables client–server web communication via a request–response cycle. Identify common http methods like get, post, put, delete, head, options, and batch.

Explore how http enables the web via a client-server request-response cycle, using methods such as get, post, put, delete, head, options, and batch to exchange html, images, and videos.

Explore how DNS records store and manage domain-name information, including A, Quad, CNAME, MX, TXT, and NS records, and how caching on resolvers and authoritative servers speeds up resolution.

Master DHCP basics to automatically assign IP addresses and network configuration parameters via a client-server model, manage leases and renewals, and decide when to use DHCP versus static IPs.

Explore the DHCP four-step IP address assignment—discover, offer, request, and ack—and how relay agents forward messages, including unicast discovery in relay scenarios and the IPv6 DHCP extension for configuration.

Trace a ping from source to destination, detailing ICMP echo request and reply, and how ARP and DNS resolution enable MAC addresses in the switch table and frame delivery.

Agree on a troubleshooting plan, then ask open-ended follow-up questions and troubleshoot layer by layer from physical to application using tools like cable testers, ping, traceroute, ipconfig, nslookup, and curl.

Explore firewall types from packet filtering at the network layer to stateless checks, and progress to stateful, proxy, and next-gen firewalls with deep packet inspection, intrusion prevention, and application awareness.

Discover how vpn creates a secure, encrypted tunnel over public networks to connect devices to a vpn server, masking ip addresses and supporting site-to-site or remote access connections.

Explore how NAT traversal enables VPN connections behind routers and firewalls, featuring UDP hole punching, IPsec NAT, and perfect forward secrecy; compare split tunneling and OpenVPN versus IPsec.

Learn how load balancers distribute traffic across servers to optimize resources and boost availability. Explore hardware versus software options, health checks, session persistence, SSL termination, and content-based routing.

Explore how load balancing algorithms distribute traffic across multiple servers, covering round robin, least connections, IP hash, weighted round robin, weighted least connections, and response-time strategies.

Explore application load balancers (albs) at layer seven, enabling HTTP/HTTPS content-based routing with path-based and host-based routing, SSL termination, and sticky sessions for microservices across AWS, Azure, and Google Cloud.

Continual monitoring sustains resilient networks with real time insights from monitoring tools, telemetry, and observability. Identify bottlenecks using flow logs, routing tables, and application latency to optimize performance.

Improve network performance across layer one and layer two by optimizing physical hardware, high quality cables and grounding, plus switches, VLANs, QoS, and redundancy protocols.

Optimize the application layer to boost performance through code improvements and caching. Apply cross-layer strategies, monitoring, quality of service, and security to support horizontal scaling and resilient networks.