Real-world network problems, solved with the tools
Subnetting, DNS outages, emails going to spam, Cisco labs, TLS: here is how students and administrators use NetTools FR in the field. Every case can be reproduced in minutes, for free.
1. Splitting a /24 network into 4 VLANs
The problem. A small business is moving from a flat 192.168.1.0/24 network to four VLANs (administration, WiFi, servers, management) with different requirements: 50, 200, 20 and 10 hosts.
The solution. The VLAN calculator generates the complete plan: IDs, optimal sizes, gateways. To move faster, the VLSM calculator assigns each segment the tightest block (best-fit), then the Cisco generator produces commands ready to paste.
Result: a consistent, documented addressing plan with no waste — instead of a spreadsheet rebuilt by hand.
2. A site stops responding after a DNS migration
The problem. After a hosting change, a client reports that “the site works at home but not at the office”. A classic symptom of incomplete DNS propagation.
The solution. The DNS response test queries the local resolver, Cloudflare and Quad9: the answers differ, and the old A record is still cached. The NS Lookup confirms the delegation, and the DNS Lookup checks the remaining TTL. Conclusion: wait for the TTL to expire — then check the HTTP status code to confirm things are back to normal.
Result: a diagnosis with hard numbers in 3 minutes, without installing dig or nslookup.
3. The company's emails are going to spam
The problem. A nonprofit finds that its signup confirmations land in the spam folder at Gmail and Outlook. No visible error on the server side.
The solution. The SPF, DKIM and DMARC validator analyzes the configuration: no SPF, no DMARC, no DKIM key detected. After publishing the records (strict SPF, DKIM at the hosting provider, DMARC in monitoring mode), a second run confirms everything is green. The raw records can be viewed with TXT Lookup and MX Lookup.
Result: deliverability restored and domain spoofing blocked.
4. Preparing a Cisco lab in 10 minutes
The problem. An instructor has to produce a consistent assignment for 15 student pairs: addressing plan, VLANs, basic configuration — with no calculation errors.
Result: consistent assignments in a few clicks, and commands ready to copy into Packet Tracer.
5. Auditing a site's security before going live
The problem. A developer wants to check the security headers and certificate of their new app before opening it to the public.
The solution. The HTTP headers checker lists the presence of HSTS, CSP, X-Frame-Options, etc. The SSL/TLS test checks the certificate chain and the days remaining before expiration. The robots.txt viewer and the sitemap checker complete the audit before indexing.
Result: a go-live checklist you can verify in 5 minutes.
6. Finding out who hosts a site and when its domain expires
The problem. Before contacting a provider or buying a domain, you need to identify the registrar, the key dates and the IP block.
The solution. The WHOIS / RDAP displays the registrar, creation and expiration dates, status and name servers — for a domain as well as an IP address. The My IP page identifies the ISP and ASN of the current connection, and the reverse DNS confirms the name associated with the block.
Result: a complete record without going through ad-ridden third-party tools.
Your turn
All these use cases can be reproduced for free, without an account. Start with the tool that matches your problem.