Networking terms, explained

The words behind the numbers: what they mean, what counts as good, and how to measure them yourself.

• BufferbloatWhy the delay shoots up while your line is busy, and how to fix it on the router.
• CertificatesHow a website proves who it is, and why a connection sometimes isn't trusted.
• DNSThe internet's address book, which turns names like example.com into addresses.
• Hops and TTLHow traffic crosses the internet one router at a time, and how traceroute finds each one.
• ICMP and TCP PingTwo ways to time a host, and why one may answer when the other doesn't.
• IP AddressesThe numbers devices are reached by: public and private, IPv4 and IPv6.
• JitterHow much the delay changes from one moment to the next, and why calls and games care.
• LatencyHow long a round trip to a host takes, in milliseconds, and what counts as good.
• Packet LossThe share of packets that never arrive, and when loss is real.
• PortsThe numbered doors on a device that each service listens behind.
• Subnets and CIDRHow a prefix like /24 says which addresses belong to one network.
• Wi-Fi Bands and ChannelsWhy 2.4, 5 and 6 GHz behave differently, and how networks on the same channel share the air.
• Wi-Fi Signal: RSSI, Noise and SNRWhat the numbers behind the Wi-Fi bars mean, and which ones to watch.