Read traceroute results from Düsseldorf: hops, reply times, asterisks, partial paths and practical next steps when investigating connectivity.
DKIM selectors, public keys, RSA and Ed25519 explained. Understand what a DNS check can and cannot establish.
Understand SMTP STARTTLS: port 25, certificate verification and the limits of a server-side mail check.
Understand the results of an email domain check and distinguish receiving, sending policies and actual message authentication.
MX priorities, mail server names, implicit delivery targets and Null MX explained.
SPF records, include dependencies and the limits of static domain checks.
DMARC policies, domain alignment, monitoring and inherited records explained.
How internet addressing works: IPv4, IPv6 and the differences explained.
The Domain Name System is the phone book of the internet – how it works and why it matters.
Web encryption: what HTTPS means and how SSL certificates protect your data.
Virtual Private Networks explained: how a VPN works, what it protects – and what it does not.
Checking DNS paths: what a test can establish and where its limits are.
Understand ICE candidates, mDNS, IPv4/IPv6 comparisons and the limits of a VPN check.
Why the internet is transitioning to IPv6, what differs from IPv4 and what it means for you.
Autonomous System Numbers: how global internet routing works and what an ASN tells you.
Proxy servers explained: differences to VPNs, use cases and what a proxy really hides.
The 7 layers of network communication – from physical transmission to the application layer.
When to use TCP, when UDP? The differences and use cases of both protocols.
What does a router do, what does a switch do? Differences and use cases explained.
DHCP explained: how IP addresses are automatically assigned and what the DORA process is.
CDN, DDoS protection, DNS and WAF – what Cloudflare does and why millions use it.
Step by step: Lets Encrypt, Certbot and commercial certificates.
Everything about your public IP address and how to find it.
What does ping mean, how is it measured and what is a good value?
Network ports explained: TCP/UDP ports and well-known port numbers.
Content Delivery Networks explained – how they work and why they matter.
How to change your IP address: VPN, proxy and other methods explained.
WHOIS explained: how to query domain owners and registration data.
What do 200, 301, 404 and 500 mean? All important HTTP status codes clearly explained.