We are planning to set up a webstore on VDS and need to decide whether to use our own DNS or the hosting provider's DNS. Our server will only run a store, mail, and 1s synchronization, with NJINX as the server controlled by a panel like ispmanager, vesta or webuzo.

We are concerned about consuming too much RAM and CPU on an already expensive VDS server, especially since our CMS CS-Cart is a resource-intensive engine. We are unsure which VDS tariff to choose, but believe that the optimal ratio would be at least 2-4 cores and more RAM.

It's not worth turning up your DNS. The effectiveness of this system is not guaranteed, even by the largest and most famous hosting providers and registrars who may experience DNS server failures.
They don't like to use distributed placement, which is required. To determine the necessary resources for your website, you should primarily consider the expected traffic at peak times with some margin. The coefficient of "resource engine intensity" is only one component of the formula.

It's common for ordinary users to know little about DNS and its functions. However, even a child can type in the name or English-language abbreviation of a website without understanding that it's just a convention. To understand some solutions to eliminate access problems for local networks or the Internet, it may be useful to consider the fundamental principles of DNS.

The main purpose of this technology is to convert easy-to-remember addresses into numerical form for computer recognition. DNS allows for the redirection of requests and responses, establishing communication between specific computers rather than in a random manner.

Setting up a webstore in a VDS (Virtual Dedicated Server) environment requires careful planning, particularly considering you've mentioned the use of a resource-intensive application like CS-Cart.

Considering the DNS setup, using your host's DNS might be a reasonable choice as it might keep your server's resources free for the other intensive processes you've mentioned, such as running the CS-Cart system. DNS does not generally require significant resources unless you're dealing with vast amounts of traffic, but delegating this responsibility to a dedicated DNS service means that one less process needs to be managed on your VDS. An added benefit of managing DNS off your server is increased resilience—DNS issues at your host won't make your site unreachable if DNS is handled elsewhere.

Regarding the hardware resources and the VDS tariff, you're on the right path by considering a multi-core system with abundant RAM. The exact requirements would greatly depend on the expected traffic to the website and specific functionalities of your CS-Cart setup.

As a starting point, CS-Cart suggests a server configuration with at least 2GHz CPU frequency, 2GB RAM (or more), and SSD-based storage for optimal performance. As your business grows, it might be necessary to upgrade these specifications. A flexible hosting provider that allows you to scale up your resources as needed might be advantageous.

Remember that the choice of management panel (like ispManager, Vesta, or Webuzo) also can impact your resources. Each panel has different requirements, and often they provide additional services (like mail, backups, etc.) that may consume additional system resources. Consider a panel that is light on resources, and adjourn or turn off unrequited services, if possible.

When deciding about your VDS configuration for your online store, another thing to keep in mind is the bandwidth and data transfer allocation. These allocations could impact the performance of your website, especially if you're dealing with a lot of customer traffic as well as large product images and videos. Underestimating bandwidth could lead to a slower site or additional costs. If you expect your store to grow, ensure that your plan can handle more traffic and has room for scale up.

Moreover, the storage type and capacity is another critical aspect to consider. Solid-State Drives (SSDs) are generally much faster than traditional hard disk drives (HDDs) and contribute to lower latency and faster customer experience on your site. The storage capacity will depend on your product listings and the size of your database. Consider your expected number of SKUs and the size and quantity of photos, videos (if any), and other media associated with your products.

In terms of hosting your mail server on the same VDS as your store, it is entirely feasible. However, it has drawbacks as well; if your email utilization grows high, it can start to compete with your site for resources. Outsourcing your email to a dedicated email hosting provider could be a good idea to avoid potential issues.

Lastly, regular backups are key to ensuring your data's safety. Make sure your hosting provider offers a good backup solution, or consider using a third-party service. Think about frequency (daily, weekly, etc.), storage (on-site or off-site), and restore process. Remember, the backup process can consume considerable resources, especially if done during high-traffic periods. Schedule backups during periods of low traffic, if possible.

This might seem like a lot to consider, but given you plan on running a resource-intensive software like CS-Cart, it is crucial to ensure you're getting a VDS that meets your needs without being overkill. Also, working with a hosting provider that offers excellent scalability and customer support can significantly ease the process.

If you want to further optimize your system resources, you can look into using Content Delivery Networks (CDNs) and caching solutions. A CDN would serve your content (especially static content like images, scripts, and stylesheets) from a network of servers spread around the world, potentially reducing the load on your server and speeding up the delivery of content to your users. Popular options for CDNs include services like Cloudflare and Amazon CloudFront. There are also many CDN plugins available for CS-Cart that may simplify the integration process for you.

Caching is another key to efficient resource use and speed. By storing the results of common database queries or HTTP requests, a caching solution can serve repeated requests much faster and reduce server load. Varnish, for instance, is a well-regarded HTTP accelerator used for caching. CS-Cart also has built-in caching systems you can fine-tune.

Separating your database from your web server might be another long-term strategy for optimization. Although it adds complexity to your setup, you could consider moving your database (MySQL, MariaDB, PostgreSQL, etc.) onto a separate VDS. This way, the database engine can utilize the full resources of its server, and the web server can use all of its resources to process HTTP requests and serve static files. Database optimization, such as regular clean-ups of old shopping carts and other unnecessary data, is helpful to keep it running smoothly.

In terms of security, an SSL certificate is essential for encrypting customer data and establishing trust with your users. Depending on your hosting provider or DNS setup, acquiring and installing an SSL certificate could range from manual to fully automated (such as with Let's Encrypt). Enable automatic updates for your server software and CS-Cart installation, if available.

Fully utilizing the monitoring and logging capabilities of your system can be handy. They help you track system usage and change resource allocation as needed, spot issues or inefficiencies before they become a problem, and troubleshoot the issues when they do occur.

Ultimately, running an online store comes with some challenges. Ensuring your server is optimized to handle your load while providing a smooth experience for your users takes some planning and ongoing oversight. However, with the right strategy and tools, this is an achievable goal.