Below is a glossary of terms often times used when discussing Virtual Private Servers, web hosting, and networking. Knowing what these following terms mean should help you navigate hosting provider websites and tutorials. Not all of the following terms are concrete in meaning and could be used to mean a slightly different concept. The glossary below is ordered alphabetically and tries to focus only on terms used when discussing virtual private servers.
AUP stands for Acceptable Use Policy. This policy outlines what services the hosting provider permits and prohibits.
Auto Scaling is a feature that automatically adds or removes resources from your virtual private server to keep up with the current work load. This helps to cut costs during slow periods of time and then keeps up with demand during peaks.
Bare metal is the physical server used for hosting. It is generally the same as “dedicated server”, but a dedicated server only has to ensure certain resources and doesn’t essentially have to be bare metal. Bare metal servers are not in a virtual environment unless you create them on the server.
Block storage is a hard disk that is attached to the server through fiber channels or iSCSI and is not physically present in the current server. Block storage is treated the same as a regular hard disk, this allows you to modify the file system type and perform block level backups. Many VPS providers allow for block storage to be attached to your server where it will appear as a second hard drive on the system.
A cloud server is any server that is not local and is accessed through the internet. Any server you decide to purchase online that isn’t going to be delivered to your door is a cloud server.
A container is an operating system inside of another operating system that uses the same kernel. It’s similar to a virtual machine but containers do not require a hypervisor to run. Containers have the benefit of increased speed and less system resources to run. As for drawbacks, containers must use the same kernel and physical hardware is shared with all of the containers. Common container tools include Docker and FreeBSD Jail.
A co-location is a datacenter that rents out physical space for your servers. Co-locations allow you to use your own hardware in a datacenter without having to perform the networking, security, and managing of a datacenter. Co-locations generally rent out by rack units, half racks, full racks, and server cages.
A cron job is a time scheduled task (shell script, command) that runs at certain times during the day, week, month, and year. These tasks are often used to clear temporary data, to rotate logs, and to run tasks that would otherwise be bothersome to run manually on a daily basis.
A crontab stands for “cron table” and is used to create the schedule for cron jobs. Crontabs can be set by the root account or users and the task will run from their account. The crontab schedules tasks by using 5 columns, minute, hour, day of month, month, and day of week.
DDoS Protection is a service that helps to mitigate distributed denial of service attacks by dropping packets that are not legitimate requests before reaching your server.
File storage is remote storage on an existing file system. You can think of file storage as transferring files to a different computer for storage where you only have control over the files and not any control over the underlying file system.
A floating IP is an IP address that can be easily reassigned to a different server. Floating IP addresses are often used for IP Failover in high availability systems as a method to route traffic to a different server if the previous server were to fail.
FQDN stands for Fully Qualified Domain Name. A FQDN is a domain name with a top-level domain extension that specifies all levels of the domain. Fully qualified domain names are used to uniquely identity devices from other hosts.
High availability is the act of configuring a service to be available even if parts of the infrastructure have failed. Instead of having a single web server, your would have two or more that can be used if the first server were to fail. The goal is to eliminate all single points of failure.
An instance is a single server instance. In VPS hosting an instance usually refers the virtual server you have purchased and have resources allocated to. Stopped instances are servers that are not currently running but resources could still be dedicated to them (IP address, disk space) for when they start again.
ISO is a file format that stores an archive of a optical disc. These files can contain operating system installation media that can be used to install operating systems on virtual machines easily.
Kernel-based Virtual Machine (not to be confused with KVM switch) is a full virtualization solution for Linux. KVM allows one server to run multiple virtual machines running unmodified operating systems. Each virtual machine has its own private virtual hardware (network cards, disk, etc).
LAMP is a term used when describing the software Linux, Apache, MySQL, and PHP. Many web servers require all of these services to run properly.
LEMP is a term used when describing the software Linux, Nginx, MySQL, and PHP. These services are used for the majority of websites and will often be brought up if your server is being used for a website.
Load balancing is when requests are spread out across multiple servers to improve performance. There are many types of load balancing from round-robin DNS to reverse proxies. A website would often have at least three servers, a load balancer and then two web servers. The load balancer will take incoming requests and distribute them evenly to the two web servers to cut the work load of a single server in half.
Looking Glass is a set of online tools offered by hosting companies that allows you to perform network tests from their servers. Common tools include ping, traceroute, and speed tests via file downloads.
MEAN is another acronym that describes the software that is installed on a server. MEAN stands for MongoDB, Express, AngularJS, and Node.js.
A NoSQL database is a storage system that has storage and retrieval methods that are not structured similar to relational databases. Instead of queries you would use key-value pairs, object database, or document stores. A few common servers that use NoSQL are Memcached, MongoDB, and Redis.
A null route is a network route that goes nowhere. Packets to a null route are dropped rather than being forwarded to the destination. Null routes are commonly used to mitigate large DDoS attacks and prevent them from affecting other services on a network.
Offsite backups are backups that are stored in a different data center or storage facility. Offsite backups are important in the case of fires and natural disasters that cause damage to a data center. With offsite backups you reduce the risk of losing important information in the case of unexpected disasters.
Overselling is the act of selling more servers or hosting services than the server can handle. Shared hosting providers are often guilty of overselling their services which degrade performance for every website.
Pay as you Go
Pay as you Go is a payment structure where you pay for your services at the time you purchase them. Pay as you go usually is split into monthly payments and allows you to cancel at any time, unlike contracts where you may be locked in for a year or two. Contracts usually have the benefit of additional savings but lacks the freedom of Pay as you Go.
A private network is a network that is not available publicly on the web. When VPS providers mention private networking, this means that multiple servers from a provider can communicate through a private network. Private networks increase speed between servers that work together and can reduce risk by not publicly opening ports to your database and other services. See our post on VPS Providers that offer Private Networks.
Provisioning is the process of preparing a network for a new service. For virtual private servers, provisioning is when a new server is created for use.
The PTR record is the DNS record type used for reverse DNS. The PTR record contains the domain name associated with an IP address.
Reverse DNS (rDNS)
Reverse DNS is a lookup to determine the domain name associated with an IP address (reverse of a standard DNS lookup). Many mail servers require the reverse DNS to be configured properly or mail will be marked as spam or dropped.
Serial Console Access
Serial Console Access when discussing virtual private servers often is used to describe a terminal that can be accessed through the providers control panel. This is useful if you were to get locked out of SSH due to a bad firewall or configuration problem. Serial Consoles should not be a replacement for SSH.
Serverless computing is a system where parts of your application will run based on events. There is still a server in serverless computing, but it’s managed by your provider. Serverless computing lets you run parts of your application that is generally less frequent without having to create more servers.
Service-level agreement is an official agreement that outlines the quality and availability of the service the company is offering. In VPS hosting, the SLA is generally displayed as an uptime guarantee.
A snapshot is a record of the state of a machine at a point in time. Snapshots are often created when the machine is properly configured. In the future the snapshot can be used to restore the machine to its past state or to create a new machine that is identical to the snapshot machine. Multiple snapshots can be created, the newer snapshots will only store the blocks of data that have changed since the previous snapshot.
Virtualization is the act of running a virtual version of the operating system inside of another system. The virtual system doesn’t physically exist but can perform nearly all tasks as a regular system. Networking cards, hard drives, disc drives and other hardware is also virtualized for the system to use. Virtual systems are isolated from each other and act as if they were independent machines.
A virtual network is a network that is created virtually and does not have physical switches and routers. Many virtual private servers use virtual networks when communicating with other servers on the same network. Virtual networks are indistinguishable from physical networks on a software level.