NETLAB Tools — t00l.thearties.com

Network troubleshooting toolbox — runs 100% in your browser, queries via DNS-over-HTTPS. No data leaves your machine except DNS queries to public resolvers.

IPv4 Calculator

IP address Prefix length or mask (e.g. 24 or 255.255.255.0)

Enter IP + prefix → results here

Subnet Division

If you have a network with prefix supernet: How many /subnets fit? Network base (optional, e.g. 192.168.1.0)

Enter prefix lengths → results here

DNS Lookup (dig-style)

DNS Propagation Check

Queries 4 public resolvers independently. Different answers = propagation still in progress or DNS cache not expired.

IP Info & ASN Lookup

WHOIS Lookup

Domain

Results appear here…

DNS Cache Clear — client-side

Public DNS (1.1.1.1, 8.8.8.8) is NOT under your control — you can't "clear" it. TTL controls how long caches hold a record. Flush YOUR machine's cache:

Windows:  ipconfig /flushdns
macOS:    sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder
Linux:    sudo systemd-resolve --flush-caches   (or: sudo systemctl restart systemd-resolved)
Router/AP: reboot it, or flush in admin UI

Force a fresh lookup from a resolver you control:

curl -H "accept: application/dns-json" "https://cloudflare-dns.com/dns-query?name=example.com&type=A"
dig @1.1.1.1 example.com A   # bypasses local cache, queries resolver directly