Fix a site that isn't responding

None of the four common addresses for your domain returned a working page. Work through DNS, then the server, then the firewall.

15–30 min

why this matters

Every minute your domain does not answer, every ad click, email click and search visit lands on an error page. This is the single most expensive technical fault there is.

Step by step

1
Confirm the domain still resolves
Look up the A record for your domain. If nothing comes back, DNS is the problem — not your server. Check that the domain has not expired and that its nameservers point at the DNS provider you actually use.
```
dig +short A example.com
dig +short NS example.com
```
2
Point the A record at your live server
In your DNS provider, add or correct an A record for the root domain and a CNAME (or second A record) for www, both pointing at your current hosting IP or hostname. Keep the TTL at 300 seconds until you have confirmed it works.
```
A     @      203.0.113.10
CNAME www    example.com
```
3
Check the server is actually listening
SSH into the host and confirm the web server process is running and bound to ports 80 and 443. Restart it if it has crashed, then read the error log for the reason it stopped.
```
sudo systemctl status nginx
sudo ss -tlnp | grep -E ':80|:443'
```
4
Open the firewall
Cloud providers block inbound traffic by default. Allow ports 80 and 443 from anywhere in both your host firewall and your provider's security group.
```
sudo ufw allow 80/tcp && sudo ufw allow 443/tcp
```
5
Add uptime monitoring so you find out first
Once the site is back, set a check that hits your homepage every minute from more than one region and alerts you by SMS or push, not just email.