Networking
TCP/IP, DNS, NAT, reverse proxies, TLS, and connectivity concepts.
What is the difference between TCP and UDP?
TCP is connection-oriented and reliable, while UDP is connectionless and faster but unreliable.
What is DNS and why is it important?
DNS translates domain names into IP addresses.
What is a reverse proxy?
A reverse proxy sits in front of backend servers and forwards client requests to them.
What is the difference between Layer 4 and Layer 7 load balancing?
Layer 4 balances traffic based on transport data like IP and port, while Layer 7 uses HTTP-level details like host and path.
What is NAT and why is it used?
NAT translates private addresses to public ones so internal systems can reach external networks.
What is TLS termination?
TLS termination means decrypting HTTPS traffic at a proxy or load balancer before forwarding it.
What is DNS TTL?
TTL defines how long DNS records are cached by resolvers.
What is latency?
Latency is the time it takes for data to travel from source to destination.
What is an IP address?
An IP address is a unique identifier for a device on a network.
What is the difference between IPv4 and IPv6?
IPv4 uses 32-bit addresses, while IPv6 uses 128-bit addresses.
What is a subnet?
A subnet is a smaller network inside a larger network.
What is CIDR?
CIDR defines IP ranges using prefix notation like /24.
What is a private IP address?
A private IP is used inside internal networks and is not routable on the internet.
What is a public IP address?
A public IP is accessible from the internet.
What is a port?
A port identifies a specific service on a device.
What is a firewall?
A firewall controls incoming and outgoing network traffic.
What is a network protocol?
A protocol defines rules for communication between devices.
What is the difference between HTTP and HTTPS?
HTTPS is HTTP with encryption using TLS.
What is a load balancer?
A load balancer distributes traffic across multiple servers.
How does DNS resolution work?
DNS converts domain names into IP addresses through a series of queries.
What are common DNS record types?
A, AAAA, CNAME, MX, and TXT.
What is a VPC?
A VPC is a virtual private network in the cloud.
What is routing?
Routing determines how traffic moves between networks.
What is a gateway?
A gateway connects different networks.
What is a proxy server?
A proxy forwards requests between clients and servers.
What is a forward proxy?
A forward proxy sits between client and internet.
Why is a reverse proxy used?
To manage traffic to backend servers.
What is a TLS handshake?
It establishes a secure encrypted connection.
What is a CDN?
A CDN caches content closer to users.
What is the difference between latency and throughput?
Latency is delay, throughput is data transfer rate.
What is a packet?
A packet is a unit of data sent over a network.
What is bandwidth?
Bandwidth is the maximum data transfer capacity.
What is the TCP three-way handshake?
SYN, SYN-ACK, ACK.
What is retransmission in TCP?
It resends lost packets.
What is a timeout?
A timeout is the waiting period before retrying or failing.
What is a health check?
It checks if a service is alive and working.
What is a DDoS attack?
A DDoS attack overwhelms a system with traffic.
What is rate limiting?
It limits how many requests a client can make.
How do you achieve zero downtime deployments?
Using load balancing, rolling updates, or blue-green deployments.