Networking & DNS
IP addresses, reverse DNS, ports and traffic.
72 guides · page 4 of 4
Set your server hostname and reverse DNS
Change the server's hostname, point DNS records at your IP, set reverse DNS in the control panel and check that forward and reverse lookups match.
Split-horizon DNS explained: different answers inside and outside
What split-horizon (split-brain) DNS is, why offices and private networks use it, how to implement it with BIND views, Unbound or a hosts-file approach, and pitfalls to avoid.
TCP vs UDP explained for server owners
TCP sets up a connection and guarantees delivery; UDP sends independent datagrams with no handshake. Learn the difference, which services use each and why firewall rules must name the protocol.
The dig command: DNS lookups explained with examples
Use dig to query A, MX, TXT, NS and other records, ask a specific nameserver, trace delegation from the root and check propagation, SPF, DKIM and DNSSEC.
Troubleshoot MTU problems: hanging pages, stuck SSH and slow VPNs
Recognise MTU and fragmentation problems, find the right MTU with ping, and fix it on Linux, Windows, WireGuard and Docker networks.
Understanding bandwidth: incoming vs outgoing traffic
What counts as traffic, how incoming and outgoing data differ, how traffic differs from port speed, and how to check usage on Linux and Windows.
Web server ports explained: 80, 443, 8080 and 8443
What ports 80, 443, 8080 and 8443 do, why HTTPS lives on 443, when alternate ports make sense, and how to check which process is listening on each one.
Website still showing the old site after migration or DNS change
Moved your site but still see the old version or old host? Learn how to check which IP your domain resolves to, clear caches at every layer and finish the DNS switch.
What is a server hostname?
A hostname is the name a server uses for itself. Learn how it differs from a domain name and an IP address, how to choose a good one, and how it relates to DNS and reverse DNS.
What is latency (ping) and why it matters for your server
Learn what latency is, how distance and routing affect it, how to measure ping on Windows, Mac and Linux, and when it matters for websites, games, trading and RDP.
What is reverse DNS (rDNS) and why it matters
Reverse DNS maps an IP address back to a hostname using a PTR record. Learn how it differs from normal DNS, why mail servers check it, and how to look it up from your own computer.
Wildcard DNS records explained: how *.example.com works
How wildcard DNS records match undefined subdomains, their rules and limits, typical uses for SaaS and multisite, interaction with MX and CNAME, and the risks to avoid.
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