Web Hosting Terms Glossary: What Do DNS, cPanel, Inodes and VPS Mean?

What are web hosting terms, and how should you read this glossary?

Web hosting terms are the technical concepts that describe the servers, domain names, DNS, security and backup layers that keep a website online. For each term, this glossary first gives a short definition. It then explains what the term means for you as a site owner and where to go for a deeper guide.

We are Talha Aslan and team, a web design and digital marketing team, not a hosting company. Because of that, we based every definition on official documentation, RFC standards and control panel vendor docs. Our goal is simple: you should not get lost in web hosting terms when you talk to a provider or compare plans.

You can use the glossary in three ways:

• Quick lookup: find an unfamiliar word from a support reply and read the first paragraph of that section.
• Plan comparison: read the bandwidth, inode, quota and SLA sections, then line up the limits in each offer.
• Going deeper: follow the link in each section to the related setup or configuration guide.

In practice, the terms follow a roughly alphabetical order. However, we grouped closely related ideas, such as DNS records, into one section. If you want the full hosting decision first, start with our guide to choosing web hosting. Looking for SEO, Google Ads or Meta Ads vocabulary instead? Those live in our separate digital marketing glossary.

What is an A record, and what is an AAAA record?

An A record is the DNS record that points a domain name to an IPv4 address. When a browser asks for example.com, the DNS resolver checks the A record and returns an address such as 192.0.2.10. Specifically, the record type comes from RFC 1035.

An AAAA record does the same job for IPv6. RFC 3596 defines it as a record that carries a 128-bit IPv6 address, for example 2001:db8::10. If your server supports IPv6, keeping both records helps visitors reach you from any network.

Here is what it means for you. When you switch hosts or your server IP changes, the A and AAAA records are the first things to update. For example, a stale AAAA record can make a site that works over IPv4 fail on some mobile networks. So if you do not actually serve traffic over IPv6, remove old AAAA records.

A CNAME record is also a close relative you will meet often. It maps one name to another name, for example www.example.com to example.com. You can check your live records with our DNS lookup tool.

What is bandwidth, and what does monthly data transfer mean?

Technically, bandwidth is the amount of data a connection can carry per second. In other words, it is a speed. Hosting plans, however, often use the same word for monthly data transfer, meaning the total data your site sends to visitors in a month. When you read an offer, ask the provider which one they mean.

Example calculation: say your average page weighs 2 MB and you get 50,000 page views a month. Then rough transfer comes to around 100 GB. Caching and a CDN bring that number down, while large video files push it up fast. Still, treat this as an estimating method, not a guarantee.

Unlimited bandwidth also deserves a closer look. Many providers apply a fair use policy, so the contract details matter more than the plan name. We walk through the math and the upgrade signals in our hosting bandwidth guide.

What is a CDN, and does every site need one?

A CDN (content delivery network) is a network of edge servers around the world that cache your static files, such as images, CSS and JavaScript. Visitors download those files from the nearest edge server instead of your origin server. As a result, latency drops and your main server carries less load.

For a site owner, a CDN brings three benefits. First, pages load faster for visitors far from your server. Second, your origin handles traffic spikes more calmly. Third, many CDN providers include basic attack filtering. That said, it is not mandatory for every site. If nearly all visitors are in the same country as your server and traffic is steady, the gain may be small.

Setting up a CDN usually means changing your nameservers or a CNAME record, so read the DNS section too. If your site already feels slow, our guide on server-side causes of a slow website helps you find the real bottleneck first.

What are cPanel and WHM?

cPanel is one of the most widely used web-based control panels for shared hosting and VPS plans. It lets you manage files, email accounts, MySQL databases, SSL, cron jobs and backups without touching the command line. In other words, this is the screen you log in to as a site owner.

WHM (Web Host Manager) is the server administrator side of the same software. With WHM you create accounts, define packages and change server-wide settings. On shared hosting, therefore, you will not have WHM access. You only use WHM with a reseller plan or your own VPS.

Knowing the difference speeds up support tickets. For example, a missing PHP extension is often a WHM-level setting, so your provider has to handle it. For a menu-by-menu tour, see our beginner's guide to cPanel.

What is a cron job?

A cron job is a scheduled task that runs a command or script on a Linux server at times you define. Specifically, you write these tasks into a crontab file. Each line holds a time expression made of five fields, minute, hour, day of month, month and day of week, followed by the command to run.

Typical uses for a site owner include moving WordPress scheduled tasks to a real cron, running the Laravel scheduler, taking a nightly database dump or clearing a cache. In cPanel you find this under Cron Jobs. On a VPS, you edit it with crontab instead.

# minute hour day month weekday command
30 3 * * * /usr/bin/php /home/user/public_html/task.php

The example above runs a PHP script every night at 03:30. Cron trusts the system clock, so a drifting clock means jobs fire at the wrong time. For that reason, keep server time in sync with NTP time synchronization. For syntax and debugging tips, read our cron job and crontab guide.

What is DNS, and how does a domain find its server?

DNS (Domain Name System) is a distributed database that translates human-readable domain names into the IP addresses computers use. When a visitor types example.com, the browser first asks a resolver. The resolver then reaches the authoritative nameserver and gets the A, AAAA or CNAME record.

Every record has a TTL (time to live) value. Put simply, TTL tells resolvers how long they may cache the record. What people call DNS propagation is really those caches expiring. Lowering the TTL before a migration means the change shows up faster.

The key rule for site owners: know where your DNS records live. They can sit at your domain registrar, in your hosting panel or at a CDN provider. As a result, a change made in the wrong place does nothing. You can confirm which records are live with the DNS lookup tool. If a domain does not resolve at all, our NXDOMAIN error guide gives a clear diagnostic order.

What is a domain name, and who actually owns it?

A domain name is the unique address people type to reach your site, such as example.com. You register it through a registrar for a fixed term. If you do not renew in time, someone else can then register it. In practice, a domain is not property you buy once; it is a registration you keep renewing.

The critical point for site owners is that the domain sits in an account you control, under your company name. A domain held in an agency account or a former employee's account causes real trouble when that relationship ends. You can check the registrant details and expiry date with our WHOIS lookup tool.

Domain registration and hosting are separate services. You can register the domain with one company and host the site with another. Nameservers or DNS records then connect the two. If you are picking a new name, our guide on choosing a domain name for your business covers extensions and brand fit.

What are FTP and SFTP, and which one should you use?

FTP (File Transfer Protocol) is an old protocol for moving files between your computer and a server. Classic FTP sends your username, password and file contents unencrypted. Therefore, anyone listening on the same network can read them.

SFTP is a separate file transfer protocol that runs inside an SSH connection and encrypts all traffic. However, despite the similar name, SFTP is not an encrypted version of FTP. The method that wraps FTP in TLS has its own name: FTPS. If your provider supports them, prefer SFTP first and FTPS second.

Our advice is simple. When you give access to an agency or developer, never share your main cPanel password. Instead, create a separate account limited to the right folder and delete it when the work ends. We show each screen in our guide on creating an FTP account in cPanel.

What is an inode, and why does the limit fill up?

An inode is the data structure that Linux file systems keep for every file and folder. It stores details such as owner, permissions, size and where the data sits on disk. In practice, every file and every folder uses one inode. So the inode count is a second limit, independent of disk space.

On shared hosting, providers often set an inode limit per account. The CloudLinux documentation also lists inodes among its account limits. Once you hit the limit, you cannot create new files, even with half your disk empty. As a result, incoming email, plugin updates and cache writes all stop.

The usual inode hogs are thousands of tiny cache files, old backups nobody deleted, mailboxes full of unread messages and session files. Start with the cache folder, then move old backups off the server. If the problem keeps coming back, find the source that creates the files instead of simply buying a bigger plan.

What is an IP address, and is a shared IP a problem?

An IP address is the numeric address that identifies every device and server on the internet. IPv4 addresses look like 198.51.100.25, and IPv6 addresses look like 2001:db8::25. Your domain's A and AAAA records point to these addresses.

On shared hosting, hundreds of sites can sit on the same IP address. The server knows which site you want from the domain name your browser sends. On HTTPS, for example, an extension called SNI handles this. As a result, a shared IP does not stop you from installing an SSL certificate.

A dedicated IP usually matters when you want to manage your own email reputation. It also helps when a payment or integration service requires an IP allowlist. You can see which IP your server shows with our IP lookup tool. The record that maps an IP back to a name is the PTR record; we cover it in the MX section.

What are disk quota, LVE and CageFS?

Disk quota is the total storage your hosting account may use. On shared servers, however, disk is not the only limit. Providers also cap CPU, memory and concurrent processes per account. One common technology for enforcing these caps is LVE from CloudLinux.

LVE (Lightweight Virtual Environment) puts each hosting account into its own resource box at the kernel level. According to the CloudLinux limits documentation, the main limits are these:

• SPEED: the CPU power the account may use.
• PMEM: the physical memory ceiling.
• IO and IOPS: disk throughput and read or write operations per second.
• EP: concurrent entry processes into the web server.
• NPROC: the total number of processes in the account.

CageFS locks each user inside a virtualized file system. That way one account also cannot see other accounts or sensitive system files. Read more in our article on CageFS account isolation. As a site owner, watch the resource usage screen in cPanel to see how often you hit these limits.

What is an MX record, and why do emails go missing?

An MX record is the DNS record that tells the world which mail server should receive email for a domain. Each MX record has a preference value, and RFC 1035 states that lower values take priority. Additionally, several MX records give mail a fallback path when the primary server is down.

Here is the practical side. If you moved company email to Google Workspace or Microsoft 365, your MX records must point to that service. During a hosting migration, copying the old zone with a stale MX record keeps mail flowing to the old server. Worse, nobody may notice for days.

Deliverability depends on more than MX. The sending server's IP also needs a matching PTR record for reverse DNS. To understand how mail travels between servers, see our explainer on the mail transfer agent (MTA).

What is a nameserver, and when should you change it?

A nameserver is the server that answers authoritatively for a domain's DNS records. The nameserver addresses you set at your registrar tell the internet which server to ask about your domain. The NS records in DNS also show that delegation.

Changing nameservers moves the management of the whole DNS zone, not just one record. Your A, MX, TXT and every other record now come from the zone on the new nameserver. Consequently, if you switch before copying every record, email, verification records or subdomains can break.

So when should you change nameservers, and when only the A record? If your host also runs DNS and you are moving every service there, a nameserver switch is practical. On the other hand, if your email lives with another service, updating only the A and AAAA records is safer. We collected the pre-move checks in our hosting migration checklist.

What is a PHP version, and why should you keep it current?

The PHP version is the release branch of the interpreter your server uses to run your site's PHP code. WordPress, WooCommerce and Laravel all run on PHP. Consequently, the version you pick affects both compatibility and security.

The PHP project publishes the lifecycle of each branch on its supported versions page. According to that page, each branch gets two years of active support after release, then two years of security fixes only. After that, support ends completely, and new vulnerabilities in that branch stay unpatched.

The practical path is to test first. Switch a staging copy to the new version, check plugin and theme warnings, then update the live site. In cPanel you make this change with MultiPHP Manager or PHP Selector; the steps are in our guide on changing the PHP version in cPanel.

What is SSL/TLS, and how does it relate to HTTPS?

SSL/TLS is the security protocol that encrypts traffic between the browser and the server and verifies the server's identity. SSL is the name of the older protocol. Today's protocol is TLS, but the market still calls certificates SSL certificates. The current version of TLS is defined in RFC 8446.

HTTPS is simply HTTP carried over TLS. In other words, installing a certificate is the precondition for serving your site over HTTPS. If the certificate expires, browsers show visitors a security warning. That hurts trust and sales directly, so do not let it lapse.

Two checks cover most site owners. First, make sure the certificate renews automatically. Then confirm that every URL redirects permanently from HTTP to HTTPS. You can see certificate status with our SSL checker. We explain certificate types in detail in what is an SSL certificate.

What are SLA and uptime, and what percentage is enough?

Uptime is the share of time a service stays reachable during a given period. An SLA (service level agreement) is the provider's written commitment to that share, plus the compensation that applies if they miss it. In short, uptime is a measurement and the SLA is a contract.

Example calculation: in a 30-day month, 99.9 percent uptime allows about 43 minutes of downtime. At 99.99 percent, however, that shrinks to about 4 minutes in the same month. This is pure math; real downtime depends on the provider and the infrastructure.

When you read an SLA, check three details. Does planned maintenance count? Who does the measuring? What is the remedy? In most contracts, the remedy is a credit on your next invoice, not lost revenue. That is why a critical online store should run its own independent monitoring and log outages itself.

What is SSH, and does a site owner need it?

SSH (Secure Shell) is the protocol that gives you encrypted command-line access to a server. If you manage a VPS or dedicated server, you do most of the work over SSH. For instance, that includes installing packages, restarting services, reading logs and moving files.

On shared hosting, SSH is often off, and providers enable it only on request. If you run a WordPress site from a panel, you may never need it. In contrast, a Laravel, Node.js or Git-based deployment moves much faster with SSH access.

The moment you enable SSH, your security responsibility grows too. Switch from passwords to key-based login, disable direct root login and add protection against brute-force attempts. We cover these hardening steps with commands in our swap file and SSH hardening guide.

What are a VPS, a VDS and a cloud server?

A VPS (virtual private server) is a virtual server carved out of one physical machine by virtualization software. It also has its own operating system and root access. Compared with shared hosting, it gives you more control. However, most of the maintenance, updates and security now fall on you.

VDS (virtual dedicated server) is less common in US and UK hosting language. Where providers use it, it usually means a virtual server whose CPU and memory are not shared with other customers. Still, the definition varies by company, so check the resource guarantee in the contract, not the plan name.

A cloud server draws resources from a pool of servers. You can usually scale it up within minutes and often pay for what you use. We compare all three by cost and use case in our VPS vs cloud server vs VDS guide. For a whole physical machine of your own, see what a dedicated server is.

What is a backup, and can RAID replace it?

A backup is a copy of your site's files and database stored somewhere independent of the live system. A good backup lets you restore the site to a specific date even if the whole server disappears.

RAID is a disk setup that uses several drives as one logical unit. For example, some RAID levels keep the system running when a drive fails. However, RAID is not a backup. A file you delete by mistake, or data that ransomware encrypts, changes on every drive at once. We explain the levels in our RAID levels guide.

Test your backup with these questions:

• Does the backup live somewhere other than the server that runs the site?
• Does it cover both files and the database?
• When did you last run a restore test?
• How many days back can you go?

For a complete plan, read our website backup strategy guide.

Web hosting terms side by side: shared, VPS, VDS, cloud or dedicated?

The web hosting terms in the sections above come together most when you compare hosting types. Next, the table below gives a short summary of control, responsibility and typical use. We do not list prices or performance figures, because those vary widely by provider and plan.

Do not skip the maintenance column. Every scenario that gives you root access also hands you updates, firewall rules and backups. Among all web hosting terms, this is the one people overlook most.

Do web hosting terms mean you have to run everything yourself?

No. Learning web hosting terms helps you ask the right questions, but running servers is a separate skill and time investment. To be honest, for most company websites and small online stores, the most efficient route is to leave the technical layer to a good provider.

These tasks usually belong with your hosting provider:

1. Operating system and kernel updates, plus CloudLinux and panel license settings.
2. Server-wide firewall and attack filtering rules.
3. Hardware failures, disk swaps and RAID rebuilds.
4. Compiling server-level PHP extensions and web server configuration.
5. IP reputation work, such as getting a mail server off a blocklist.

Your part is to track domain ownership, where DNS records live, whether backups really run and whether PHP is still supported. So you can hand off the technical work, but control and decisions should stay with you. If you do decide to run your own VPS, never go live without backups and monitoring from day one.

What should you do after reading this glossary?

After reading, we suggest a short inventory of your own setup based on these web hosting terms. Above all, that inventory tells you in advance whom to call and what to change when something breaks.

• Whose name is the domain registered in, and when does it expire?
• Which panel manages your DNS, and do the MX records point to the right service?
• What are your disk, inode and LVE limits, and how often do you hit them?
• Does the SSL certificate renew on its own, and is your PHP branch still supported?
• Are backups stored off the server, and when did you last try a restore?

If you cannot answer one of these, go back to that section first. If you are launching a new site or moving an existing one, our web design service covers hosting choice, DNS setup and the launch process with you. That way, infrastructure decisions stay in line with your design and SEO goals.