Domains, Multiple Websites and HTTPS
DNS records, buying a domain on GoDaddy, Elastic IP, subdomains, hosting many websites on one server, and free HTTPS with Certbot.
About this part
People remember names, not numbers. DNS is the system that turns a name like ravindrabagale.com into an IP address. In this part you put a real website on a real domain and protect it with HTTPS.
You will learn the common DNS records: A records point a name to an IPv4 address, and CNAME records point one name to another. You will buy a domain (the example uses GoDaddy) and attach an Elastic IP so your server's address does not change. You will create subdomains like blog. and shop., and host several websites on one server using Nginx or Apache virtual hosts. Finally you will get a free TLS certificate with Certbot and Let's Encrypt, so browsers show the site as secure.
Everyday example: a single building can hold many shops, each with its own signboard. One server can host many websites in the same way, each with its own domain.
Security note: expired certificates, forgotten subdomains and wrong DNS records are common real-world weaknesses. Keeping a simple list of your domains and renewal dates prevents most of them.
Related tools. Besides GoDaddy, domains are often managed in AWS Route 53, Azure DNS, Google Cloud DNS or Cloudflare. HTTPS works the same way whether the site is a WordPress (PHP), Django, Spring Boot, ASP.NET Core or Express app, because the certificate sits on nginx or the load balancer in front.
After this part you will be able to
- Create A and CNAME records and explain TTL.
- Attach an Elastic IP so your address stays fixed.
- Host two websites on one server with name-based virtual hosts.
- Get and auto-renew a free HTTPS certificate with Certbot.
A real-world picture
Suppose we are a junior web admin at a Tata group company launching offers.example.in. You add a CNAME, wait for DNS to update, add the server block, then run Certbot. With curl -I https://offers.example.in you see HTTP/2 200 and a valid certificate. Globally, Let's Encrypt has issued certificates for hundreds of millions of websites, which made HTTPS normal everywhere. Everyday analogy: a shop signboard (the domain) and a licence on the wall (the certificate).
Beginner questions I get in class
Q. Why does my new domain not work yet?
DNS changes take time to spread, depending on TTL. Check with dig yourdomain +short.
Q. Is Let's Encrypt safe for business sites?
Yes. It is widely trusted, and its certificates are as valid as paid ones for encryption. The difference is mainly support and validation type.
Q. Do I need a separate server for each site?
No. Name-based virtual hosts let one server host many sites.
Key terms
- A record: Name → IPv4 address.
- CNAME: Name → another name.
- TTL: How long resolvers cache an answer, in seconds.
- Elastic IP: A fixed public IPv4 address for your AWS account.
- Let's Encrypt: A free, automated certificate authority.
- HSTS: A header that tells browsers to always use HTTPS for your site.
Mini case study
Suppose we are a junior analyst at Tata Consultancy Services, asked to review a new web server on AWS before launch (with the client's written approval). The checklist from this part becomes a short report: what you checked, what you found (for example "port 22 open to 0.0.0.0/0" or "directory listing on"), the evidence (a command and its output), and the fix. Clear, evidence-based reports like this are how defenders work every day.