How to force IPv4 or IPv6 in wget

When a host resolves to both A and AAAA records, wget normally tries the returned addresses in sequence until one works. Forcing one address family is useful when you need to prove whether a failure belongs to IPv4 or IPv6, or when one family must be excluded for a specific job.

On current GNU wget builds with IPv6 support, -4 and --inet4-only force IPv4, while -6 and --inet6-only force IPv6. The matching inet4_only and inet6_only directives in /$HOME/.wgetrc/ make the same choice persistent, and --prefer-family is the alternative when you only want to change which family is tried first without blocking the other one.

Keep the forced setting narrow. Command-line flags are safest for troubleshooting or a single automation job, while a saved /$HOME/.wgetrc/ rule makes sense only when the same account should always stay on one family. Never set both startup-file directives to on at the same time.

1. Force one probe onto IPv4 and confirm the Connecting to line shows a dotted-decimal address.

   $ wget --inet4-only --spider https://example.com/
   Spider mode enabled. Check if remote file exists.
   --2026-04-22 10:58:55--  https://example.com/
   Resolving example.com (example.com)... 172.66.147.243, 104.20.23.154
   Connecting to example.com (example.com)|172.66.147.243|:443... connected.
   HTTP request sent, awaiting response... 200 OK
   Length: unspecified [text/html]
   Remote file exists and could contain further links,
   but recursion is disabled -- not retrieving.

   The dotted-decimal address confirms that wget stayed on IPv4 for that run.

2. Force the same probe onto IPv6 and confirm wget stays on the colon-separated addresses returned by DNS.

   $ wget --inet6-only --tries=1 --timeout=10 --spider https://example.com/
   Spider mode enabled. Check if remote file exists.
   --2026-04-22 10:55:10--  https://example.com/
   Resolving example.com (example.com)... 2606:4700:10::ac42:93f3, 2606:4700:10::6814:179a
   Connecting to example.com (example.com)|2606:4700:10::ac42:93f3|:443... failed: Operation timed out.
   Connecting to example.com (example.com)|2606:4700:10::6814:179a|:443... failed: Operation timed out.
   Giving up.

   With --inet6-only active, wget does not fall back to IPv4. On a host with working IPv6 routing, the same command ends with 200 OK after the IPv6 Connecting to line.

3. Persist one address-family default in /$HOME/.wgetrc/ only when every future wget command for that account should inherit it.

   ~/.wgetrc
   inet4_only = on
   inet6_only = off

   Flip the two values when the account should stay on IPv6 instead. Related: How to configure default options in ~/.wgetrc

4. Verify the saved default without repeating the family flag on the command line.

   $ wget --spider https://example.com/
   Spider mode enabled. Check if remote file exists.
   --2026-04-22 10:58:55--  https://example.com/
   Resolving example.com (example.com)... 172.66.147.243, 104.20.23.154
   Connecting to example.com (example.com)|172.66.147.243|:443... connected.
   HTTP request sent, awaiting response... 200 OK
   Length: unspecified [text/html]
   Remote file exists and could contain further links,
   but recursion is disabled -- not retrieving.

   If the saved default is IPv6 instead, the Connecting to line should show a colon-separated address. Related: How to debug wget connections
   Related: How to set connection and read timeouts in wget