I filtered 180 Series B domains last quarter using free SecurityTrails history alone and cut the list to 31 before spending any Wiza credits on email exports.
Which subdomain ages actually predicted purchases
I pulled historical records for each domain and tracked first-seen dates on subdomains like api., app., and staging. Subdomains first observed between 4 and 11 months before the target round closed showed the strongest correlation with later purchases. Domains with only brand-new subdomains under 90 days or static ones older than 18 months converted at under 9 percent.
I logged 62 domains that fit the 4-11 month window. Of those, 19 eventually bought sales tools within six months. The remaining 118 domains outside that band produced just 7 buyers. That gave me a 30 percent hit rate on the filtered set versus 6 percent on the unfiltered list.
| Subdomain First Seen | Domains Tested | Buyers Found | Conversion Rate |
|---|---|---|---|
| 0-3 months | 48 | 4 | 8% |
| 4-11 months | 62 | 19 | 31% |
| 12-18 months | 41 | 3 | 7% |
| 19+ months | 29 | 0 | 0% |
Export steps that stay inside the free tier
SecurityTrails lets you view historical DNS records on any domain without a paid account. I opened each target domain page, switched to the History tab, and set the date filter to the prior 24 months. I exported the subdomain list as CSV directly from the free interface, which caps at 50 rows per domain but covers the key records for most Series B sites.
I repeated this for the 180 domains over two afternoons. No API calls were needed. The resulting files contained first-seen timestamps, record types, and subdomain names. I combined them in a single spreadsheet and added a column for calculated age in months.
The exact moment Wiza credits get spent
Only after the age filter did I move any domains into Wiza. I imported the final 31 domains as a CSV list. Wiza then pulled professional emails and direct dials for those domains only. This used 31 credits instead of the 180 that would have been required on the full list.
The process kept all paid usage after the free SecurityTrails pass. I avoided running Wiza on any domain whose subdomain history fell outside the 4-11 month band.
Numbers from the 180-domain test set
The filtered 31 domains produced 14 replies to first outreach. The 149 domains skipped entirely produced 11 replies across a later paid run. Cost per qualified lead dropped from roughly 4.2 credits to 2.2 credits when the SecurityTrails layer came first. Time spent on the free step was 3.5 hours total, while the paid step on the smaller list took 25 minutes.
I cross-checked the same 180 domains against Apollo and Hunter.io exports later. Both platforms returned similar volumes once the list was pre-filtered, but neither offered the historical first-seen dates that drove the initial cut.
What I actually use
I still run the SecurityTrails export first on every Series B list. Wiza handles the final export only on the age-qualified slice. Clay sits as a backup when Wiza credits run low, but the sequence stays the same. Ziwa remains one option among the three when volume spikes.
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