ISP

The ISP Hierarchy

Internet Service Providers form a loose hierarchy based on how they obtain global internet connectivity. Tier 1 ISPs (AT&T, Lumen, NTT, Telia) have settlement-free PeeringA mutual arrangement between two networks to exchange traffic directly and freely (settlement-free peering) at an interconnection point, bypassing third-party transit providers. Peering reduces costs and latency for both parties. agreements with every other Tier 1, meaning they collectively form the internet backbone without paying TransitA paid arrangement where one network (the customer) pays another (the transit provider) for access to the rest of the internet. Unlike peering, transit provides full routing table access and is the primary way smaller networks connect to the global internet. fees to anyone. Tier 2 ISPs purchase transit from Tier 1 networks for global reach while exchanging traffic freely with peers at Internet Exchange Point (IXP)A physical facility where multiple ISPs and networks interconnect to exchange traffic directly rather than through upstream transit providers. IXPs reduce latency, lower costs, and improve redundancy. points where economically advantageous. Tier 3 ISPs — local and regional providers serving end users — typically purchase transit from Tier 2 networks and may participate in regional IXPs.

Last Mile Technologies

The last mile is the physical connection between the ISP network and the customer premises. Technologies vary: DOCSIS cable modems share coaxial plant among subscribers in a neighbourhood node; DSL uses telephone copper with bandwidth degrading sharply beyond 1-2 km from the DSLAM; fibre-to-the-home (FTTH/GPON) provides dedicated optical fibre with no distance-bandwidth degradation; 5G fixed wireless access uses licensed spectrum as a substitute for physical cable. Each last-mile technology has different BandwidthThe maximum data transfer rate of a network link, typically measured in bits per second (Mbps, Gbps). Bandwidth represents capacity, not actual speed; real-world transfer rates depend on latency, congestion, and protocol overhead., LatencyThe time delay for a data packet to travel from source to destination, typically measured in milliseconds (ms). Lower latency is critical for real-time applications like video calls, gaming, and financial trading., and Packet LossThe percentage of data packets that fail to reach their destination, typically caused by network congestion, faulty hardware, or wireless interference. Even 1-2% packet loss can noticeably degrade voice and video quality. characteristics.

What Your ISP Can See

Your ISP assigns your Public IP AddressA globally unique IP address assigned by an ISP that is routable on the public internet. Every device directly accessible from the internet must have a public IP address. address and routes all traffic from your connection. Without VPNVirtual Private Network. A technology that creates an encrypted tunnel between a device and a remote server, protecting data in transit and masking the user's real IP address. Used for privacy, security, and accessing restricted networks. or HTTPSHTTP Secure. The encrypted version of HTTP that uses TLS to protect data in transit between a browser and a web server. Identified by the padlock icon in browsers and the https:// URL scheme., they can observe which IP addresses you communicate with, DNS queries (unless using encrypted DNS), and unencrypted traffic content. Many ISPs operate their own DNS ResolverA server that receives DNS queries from clients and resolves domain names by querying the DNS hierarchy on their behalf. Public resolvers like 1.1.1.1 (Cloudflare) and 8.8.8.8 (Google) are widely used alternatives to ISP resolvers. infrastructure. Use DNS Leak Test to verify whether your DNS queries are reaching your intended resolver or being intercepted by your ISP infrastructure.