Networking & DNS
IP addresses, reverse DNS, ports and traffic.
34 guides · page 1 of 2
Add IP addresses and change a site's IP in WHM (root guide)
Add new IPv4 addresses to a cPanel server, assign a dedicated IP to an account, change a site's IP, and set up shared IPs per reseller in WHM as root.
CDN basics and how to set up Cloudflare with a cPanel website
What a CDN does, then a step-by-step Cloudflare setup for a site hosted on cPanel: DNS import, nameserver change, SSL mode and email records.
Check and fix reverse DNS (PTR) so your email is not rejected
Find your mail server's sending IP, check its PTR record, make forward and reverse DNS match, and fix the bounces caused by missing rDNS.
Check DNS records and propagation with cPanel Track DNS and nslookup
Verify that DNS changes have taken effect: use cPanel Track DNS, nslookup and dig to look up A, MX and TXT records, understand TTL and why propagation takes time.
Check which ports are open and listening on Linux
Use ss and lsof to list every listening port on your VPS, find the process behind each one, tell localhost from public bindings and close what you do not need.
Choose the best server location: latency, packet loss and your visitors
How to pick between Germany, USA and Singapore data centres by measuring latency and packet loss from where your visitors actually are.
CIDR notation and subnets explained (/24, /32, /64)
Learn what CIDR suffixes like /24, /32 and /64 mean, how many addresses each covers, and how to use them safely in firewall allowlists and blocklists.
Common server ports and what uses them
A practical list of the ports you meet on a VPS, from SSH and web to mail, databases and Remote Desktop, with the protocol and whether each should be public or private.
Connect Google Workspace (Gmail) to a domain hosted on cPanel
Verify your domain for Google Workspace and add MX, SPF, DKIM and DMARC records in cPanel Zone Editor, so business Gmail works while the website stays on MdmHost.
Connect Microsoft 365 email to a domain hosted on cPanel
Add the DNS records Microsoft 365 needs in cPanel Zone Editor: verification TXT, MX, autodiscover CNAME, SPF and DKIM, while keeping your website on MdmHost.
Customise DNS zone templates in WHM (root guide)
Edit the DNS zone templates WHM uses for new accounts as root: default records, TTLs, SPF and CAA records, and the variables available, so every new zone is right from the start.
Diagnose network problems with ping, traceroute, nslookup, dig, curl and telnet
A practical toolkit for finding out why a website or server is unreachable: test reachability, the route, DNS answers, ports and HTTP responses.
How to run and read an MTR report (packet loss and latency)
Run MTR or WinMTR, then read loss, latency and jitter per hop correctly so you can tell real network problems from harmless router behaviour.
HTTP/2 and HTTP/3 (QUIC) explained: what they change and how to check them
What HTTP/2 and HTTP/3 improve over HTTP/1.1, why HTTP/3 runs on UDP, and how to check which version your site really serves with a browser or curl.
IP addresses explained: public, private, shared and dedicated IPs
What an IP address is, how public and private ranges differ, and when a shared or dedicated IP matters for your website, email or server.
IPv4 vs IPv6 explained
A plain explanation of IPv4 and IPv6 addresses, why IPv6 exists, how to read your server's address, and what each means when you connect to a VPS or point a domain at it.
Manage DNS records in cPanel Zone Editor (A, AAAA, CNAME, TXT, SRV, CAA)
Add, edit and delete DNS records for your domains in cPanel Zone Editor, with real examples for A, CNAME, TXT, SRV and CAA records and TTL advice.
MX records and Email Routing in cPanel (use Google Workspace or Microsoft 365)
Change MX records in cPanel Zone Editor, set Email Routing to local or remote, and connect Google Workspace or Microsoft 365 while keeping your website on MdmHost.
NAT, masquerade and port forwarding with nftables
Use nftables to masquerade VPN clients out through your VPS and forward ports to a backend with DNAT. Includes IP forwarding, forward chain rules and a complete VPN gateway ruleset.
Point a subdomain to your home IP with cPanel Dynamic DNS
Use cPanel Dynamic DNS to keep a subdomain such as home.example.com pointed at a changing home or office IP, with the update URL, router setup and a cron example.
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