Computer Networking Glossary

December 2015 · 4 minute read

This is a descriptive glossary of computer networking terms, explaining individual components and how they fit together, based on recent research and implementations.

Computer Networking

A computer network is a set of computers connected together for the purpose of sharing resources such as a connection to the Internet, a printer or a file server.

Networked computing devices exchange data with each other along network links. An example of networked devices could be a printer and computer which is configured to use the printing service within the same network. Computers which do not have authority to access the printer cannot use it.

Computer network programming involves writing computer programs that enable processes to communicate with each other across a network.

Network Application Programming Interfaces (API)

An Application Programming Interface is a set of routines that an application program uses to request and carry out lower-level services performed by the operating system. Web APIs are a software-to-software interfaces allowing applications to work together without user knowledge

Internet Protocol (IP)

An IP address is a numerical label assigned to each device (e.g., computer, printer) participating in a computer network that uses the Internet Protocol for communication.


A domain name is an identification string which can be bought via a registry. Domain names follow the rules and procedures of the Domain Name System (DNS). Any name registered in the DNS is a domain name.

Domain Name Servers (DNS)

Domain Name Servers maintain a directory of domain names and translate them to Internet Protocol (IP) addresses. This is necessary because, machines only access websites using IP addresses, whereas people prefer domain names.

DNS Zone

A DNS zone is the part of a domain for which an individual DNS server is responsible. Each zone contains a single SOA record.

DNS Records

DNS records are basically mapping files that tell the DNS server which IP address each domain is associated with, and how to handle requests sent to each domain.

A DNS (Domain NameServer) record (also known as a zone file) is a small set of instructions for resolving specified Internet domain names to the appropriate number form of an Internet Protocol address (an IP address).

A - IPv4 address

CNAME - Canonical Name

MX - Mail Exchanger which controls email routing

NAPTR - pointer?

TXT - Text like comments or untyped info.

AAAA - IPv6 Address

SRV - Services which gives locations of well-known services

Start of Authority (SOA)

Every domain must have an SOA record at the cutover point where the domain is delegated from its parent domain. For example if the domain is delegated to DNSimple’s DNS servers, we must include an SOA record for the name in our authoritative DNS records. We add this record automatically for every domain that is added to DNSimple and we show this record to you as a System Record in your domain’s Manage page.

The SOA record includes the following details:

The primary name server for the domain, which is or the first name server in the vanity name server list for vanity name servers.

The responsible party for the domain, which is

A timestamp that changes whenever you update your domain.

The number of seconds before the zone should be refreshed.

The number of seconds before a failed refresh should be retried.

The upper limit in seconds before a zone is considered no longer authoritative.

The negative result TTL (for example, how long a resolver should consider a negative result for a subdomain to be valid before retrying).

Name Servers (NS)

A name server is a specialised server on the Internet that handles queries or questions from local and remote hosts, about the location of a domain name’s various services. It translates domain names into IP addresses (or vice versa), enabling you to enter the websites name into the search bar instead of trying to remember an IP address. Name servers also have other uses such as caching answers to queries so that it can answer faster next time and transfering data between your name servers to keep them synchronised.


A hostname is a label that is assigned to a device connected to a computer network and that is used to identify the device in various forms of electronic communication.


Time to live (TTL) is a mechanism that limits the lifespan or lifetime of data in a computer or network. When you change a domain records to point at a different server, the change does not take effect immediately. Instead, it has to propagate throughout the Internet. How long this takes can depend on the current TTL, or Time to Live setting. This is typically measured in seconds, so a TTL of 3600, for example, means it might take up to an hour for the changed to propagate.