Using ipconfig /flushdns to Fix Internet Connectivity

What DNS Caching Actually Does

Every time Windows resolves a domain name like example.com to an IP address, it stores that answer in a local DNS resolver cache so it doesn't have to ask your DNS server again for a while. That's normally a good thing — it makes browsing faster. But if a site changes its IP address, if you switched networks or VPNs, or if malware or a misconfigured router poisoned an entry, that cached record goes stale and Windows keeps handing your browser a wrong or dead address, producing errors like "This site can't be reached" or "DNS_PROBE_FINISHED_NXDOMAIN" even though the site is actually fine.

ipconfig /flushdns wipes that local cache clean, forcing Windows to look up every domain fresh the next time you visit it.

Step 1: Open an Elevated Command Prompt

1. Press Win, type cmd.
2. Right-click Command Prompt and choose Run as administrator (flushing DNS doesn't strictly require elevation on most systems, but running as admin avoids permission errors on locked-down machines).

Step 2: Flush the Cache

ipconfig /flushdns

You should see:

Windows IP Configuration

Successfully flushed the DNS Resolver Cache.

Step 3: Go Further If the Problem Persists

Flushing DNS alone fixes most stale-cache issues, but connectivity problems are often layered. Run these in order if the flush alone doesn't help:

Release and Renew Your IP Address

ipconfig /release
ipconfig /renew

This drops your current DHCP lease and requests a fresh one from your router, which also clears out any bad gateway or subnet configuration your adapter picked up.

Re-register With Your DNS Server

ipconfig /registerdns

Mainly relevant on domain-joined machines — it re-registers your hostname with your DNS server, useful if internal name resolution (e.g. reaching other PCs by hostname on an office network) has broken.

Reset Winsock (for deeper corruption)

netsh winsock reset
netsh int ip reset

Step 4: Verify It Worked

Check that a domain now resolves correctly with nslookup:

nslookup example.com

If it returns a valid IP address without a timeout, resolution is working. You can also confirm the cache is actually clean by trying to display it:

ipconfig /displaydns

Immediately after a flush, this should return a mostly empty list (or repopulate quickly as you browse).

When to Suspect Something Other Than DNS Cache

• Every site fails, including by IP address: that's not a DNS problem — check your physical connection, Wi-Fi signal, or router.
• Only specific sites fail consistently: could be the site itself, a firewall/antivirus block, or your ISP throttling/blocking that domain — flushing DNS won't help here.
• Problem returns within minutes: your router or ISP's upstream DNS server may itself be serving bad records. Switching your adapter to a public resolver like 8.8.8.8 or 1.1.1.1 sidesteps a broken ISP DNS server entirely.

Quick Reference

ipconfig /flushdns      REM clear the local DNS cache
ipconfig /displaydns    REM view current cache entries
ipconfig /release       REM drop current DHCP lease
ipconfig /renew         REM request a new DHCP lease
ipconfig /registerdns   REM re-register hostname with DNS
netsh winsock reset     REM reset Winsock catalog (needs reboot)