IPv4 and IPv6 on a Lookup Page
TL;DR: IPv4 is the familiar four-part number. IPv6 is the longer address many networks now hand out alongside it. A lookup may show one, the other, or both, depending on which path your browser actually used. Neither format is “more you.” They are two numbering plans. Compare what Ipsaya shows for this visit with the address a support agent reads back, and make sure you are talking about the same family.
Two labels on one front door
A community radio station I helped last year had a new ISP that turned on IPv6 and left IPv4 in place. The streaming encoder, an older box, still announced an IPv4 address. The station manager’s laptop, which preferred IPv6, showed a long hexadecimal address on a lookup page. She pasted the long one into the support chat. The engineer searched his logs for those characters, found nothing, and told her the stream was down. The stream was up. They were describing two front doors of the same building. Once she read him the four-part address from the encoder’s status page, he found the session in a few seconds.
That mix-up is the whole lesson. Dual-stack networks speak both dialects. The dialect you see is the one your device chose for that particular connection.
How to recognize each shape
IPv4 uses four decimal numbers separated by dots, each between 0 and 255, like 198.51.100.20. IPv6 uses hexadecimal groups separated by colons, and it may compress a run of zeros with a double colon. If you see colons, you are not looking at a “broken” IPv4 address. If you see exactly four dotted chunks, you are not looking at a truncated IPv6 address. Copy the whole thing. A partial IPv6 copy is especially misleading because the compressed form already hides zeros.
- Dots and four fields: IPv4, still what many older tools expect.
- Colons: IPv6, often the path a modern phone or laptop prefers.
- Both listed: your network offered two exits and the page recorded the one this browser used, sometimes with the other available nearby.
- One disappeared after a VPN: the VPN may support only IPv4, so the v6 path went away on purpose.
Why a page might show a different family than your router
Router admin screens often list a WAN IPv4 address in a prominent box and tuck IPv6 under a separate tab. A lookup in the browser follows the browser. If the browser is happy on IPv6, the page reports IPv6 even while the router still has a public IPv4 for older gear. You can force a comparison by trying the lookup from a device that does not have IPv6, such as an old games console, or by disabling IPv6 briefly on the laptop. Do the brief test, write down both results, and turn IPv6 back on. Leaving it off forever to make a screenshot match is how you create next month’s outage.
Phones add a twist. On Wi-Fi they may show the household IPv6 prefix. On cellular they show the carrier’s addresses, which are a different pair entirely. If you switch radios and the lookup changes family and provider, the page is tracking the radio. That is what you asked it to do.
Support scripts that only have a four-box form
Some ticket forms accept only IPv4. Pasting IPv6 into them produces an error that looks like “we cannot find you.” Paste the IPv4 from the router or from a device that still uses it, and mention in the comment that the laptop also has an IPv6 address. Agents who only search one log will thank you. Agents who understand both will ignore the extra line. Either way you have not hidden a door.
Looking up someone else’s address
When you query a specific IP or a domain, match the family to the question. A domain might have an A record (IPv4) and an AAAA record (IPv6). A location result for one is not automatically the location result for the other if they are served from different sites. If you are checking where a website lives, note which record you asked about. If you are checking your own visit, believe the address the page detected for this browser rather than a record you typed from memory.
Mail clients that hide one family
Some webmail “show original” views truncate a long IPv6 source or wrap it so the double colon disappears into the next header. If you are copying from a header into a lookup, paste into a plain note first and rejoin the line before you search. A chopped v6 string will not match the laptop’s lookup even when both are talking about the same path. The radio station’s engineer would have missed a match that way too, had the long address been the one in the log.
Write down the family before you argue
The radio station lost half an hour because a long address and a short address were treated as rivals. Next time two devices “disagree,” put the two strings side by side and mark v4 or v6 before anyone says the lookup is wrong. Then decide which device the service actually sees. The numbering plan is allowed to be plural. Your notes should be plural too.
