Articles

Choose between hashing and encryption according to the property you need: confidentiality, integrity, authentication or reduced correlation. Different mechanisms solve different problems: encryption is not hashing, a VPN is not the same as an application proxy, and changing a visible identifier does not create complete anonymity.

IP geolocation approximately associates a network address with a country, region, city or provider. Its accuracy depends on the database and the connection type. A location result is neither a person’s coordinates nor proof of their physical whereabouts.

On Unix-like systems, chmod changes access permissions on files and directories. Read, write and execute permissions are set separately for the owner, the group and other users. Directory permissions have their own meaning: they affect listing names, creating or removing entries, and accessing a known path.

A browser’s “DNS error” describes a symptom, not a single root cause. A name might be mistyped, an authoritative server unreachable, a resolver might hold an older answer, or DNSSEC validation might fail. Identify the failing stage before changing a configuration.

A DNS cache keeps recent answers so every request does not need a complete lookup through the naming hierarchy. Caches may exist in an application, the operating system and the recursive resolver. Removing an answer from one of them does not immediately replace copies elsewhere.

A vendor lookup examines the MAC address of a network interface, an identifier used on the local Ethernet or Wi-Fi link. A device MAC address is not carried across the Internet as a permanent global identifier: routers use link-layer addresses appropriate to each local segment.

The TCP handshake takes place along the transport or network path. Separate the local socket, IP delivery, TCP or UDP behaviour, firewall filtering and NAT. A successful ping does not prove a TCP port is reachable, and an open port does not prove the application protocol is healthy.

When choosing an Internet provider, look beyond the advertised maximum speed or plan name. Access technology, resources, isolation, routing, peering/transit, address policy and support all matter. Two services with similar headline specifications can behave differently under load.

An exact rule, unit or bit representation explains download time more clearly than generic network troubleshooting. Before calculating, identify what is measured, the input units, and the expected output format.

When measuring Internet speed, look beyond the Mbps number. Throughput, latency, jitter and packet loss describe different properties, while Wi-Fi, Ethernet, competing devices, VPNs, routing and the test server all affect results. High throughput can coexist with poor latency under load.

Nslookup is a command-line tool for asking a DNS server about a domain or an IP address. It helps distinguish a name-resolution issue from a problem with a website or mail service. Its answer depends on the chosen resolver and its cache; it is not necessarily the authoritative source.

Traceroute gradually increases the IPv4 TTL or IPv6 Hop Limit and records routers that respond along the way. This reveals part of the route to a destination, not a guaranteed map of every packet’s path.

HTTP Strict Transport Security lets an HTTPS origin tell supporting browsers to use HTTPS for a period of time. includeSubDomains broadens the policy; preload is a separate browser ecosystem mechanism and should not be enabled casually.

HTTP status codes describe the application layer; distinguish network reachability from the web-server response. DNS can resolve, TCP/TLS can connect, and HTTP can still return a redirect or error. Status code, Location, hostname, path and URL scheme describe different parts of the transaction.

HTTP defines requests and responses between a client and a web server. HTTPS uses the same web semantics over a protected connection: data is encrypted, and the client checks that the server is authorised for the name in the address bar. This protects the exchange in transit, not the honesty of the site owner.

HTTP/2 multiplexes HTTP streams over one TCP connection; HTTP/3 maps HTTP semantics onto QUIC over UDP. QUIC provides independent streams and integrates TLS 1.3, changing loss recovery and connection establishment without changing HTTP methods or status codes.

HTTP/3 is a version of HTTP that uses QUIC instead of the familiar HTTP/2, TLS and TCP combination. QUIC runs over UDP but adds reliable streams, congestion control and secure connection establishment. Supporting HTTP/3 alone does not make every page fast.

ICMP carries control and error information for IP networks. Ping uses ICMP Echo, but ICMP also reports conditions such as an unreachable destination, an oversized packet or an expired hop limit.

Compare peering and IP transit on more than an advertised maximum speed or plan name. Access technology, resources, isolation, routing, peering/transit, address policy and support all matter. Two services with similar headline specifications can behave differently under load.

An internet speed test measures throughput between your device and a particular test server at a particular time. Most tests show download, upload and latency separately. The result depends on the server, route, local network and current load; one measurement cannot describe the performance of every website or application.

IP fragmentation and Path MTU concern packet delivery along the transport or network path. Separate the local socket, IP delivery, TCP or UDP behaviour, firewall filtering and NAT. A successful ping does not prove a TCP port is reachable, and an open port does not prove the application protocol is healthy.

Embedding an IP widget adds a page dependency: iframe or JavaScript, network requests, caching and logging. An embedded speed test or IP widget should be evaluated for HTTPS/CSP compatibility, performance budget, availability and the technical data visible to the third party.

Handling IPv4 and IPv6 in IP APIs depends on the contract between a client and an API. A client should distinguish success, validation errors, authentication failures, rate limits and temporary server errors. JSON versus XML does not change HTTP semantics, and IPv4/IPv6 values must be preserved without IPv4-length assumptions.

IPv4 and IPv6 are two versions of Internet Protocol that both operate on today’s Internet. IPv4 addresses are 32 bits long; IPv6 addresses are 128 bits long. The larger IPv6 address space does not automatically make a connection faster or safer. Performance and exposure depend on the route, network and configuration.

IPv6 link-local addresses make sense alongside the way a host identifies its local network, neighbours and route to other networks. IPv4 depends on the address, prefix length and gateway; IPv6 also depends on address scope and Neighbor Discovery. One wrong value can leave local communication working while breaking access beyond the subnet.