IPv4 Due Diligence: Your Pre-Purchase Checklist
Buying IPv4 addresses is a significant investment. A /22 block can cost $25,000-$35,000. Before committing, thorough due diligence can save you from expensive problems. Here are the 10 essential checks every buyer should perform.
1. Blacklist Status
This is the most critical check. Run every IP in the block against major DNS blacklists. Use our free IP Blacklist Checker to scan against 300+ blacklists simultaneously. Even a single blacklisted IP can cause delivery issues for your entire block.
2. WHOIS Registration Verification
Query the WHOIS database to confirm the seller is the actual registered holder. The organization listed in WHOIS should match the seller's identity. Check this through the relevant RIR's database (RIPE, ARIN, APNIC).
3. BGP Announcement History
Review the block's BGP routing history using tools like bgp.he.net or RIPEstat. Look for:
- Previous ASNs that announced the prefix
- Routing anomalies or hijack indicators
- How recently the block was announced
- Long periods of non-announcement (could indicate abandoned space)
4. Resource Type (Legacy, PI, PA)
Understand what you are buying:
- Legacy: Allocated before RIR system, fewer restrictions, may cost more
- PI (Provider Independent): Standard transferable addresses
- PA (Provider Aggregatable): Allocated to LIRs, may have additional transfer steps
5. Holding Period Compliance
Some RIRs impose holding periods. RIPE requires a 24-month hold before addresses received via transfer can be re-transferred. Verify the seller's holding period has been satisfied.
6. Abuse History
Check AbuseIPDB and other abuse databases for reported incidents. IPs with extensive abuse history may have been used for spam, phishing, or malware distribution, which can take months to clean up.
7. Geolocation Data
IP geolocation databases (MaxMind, IP2Location) may have outdated location data. If your use case is location-sensitive (CDN, content delivery), verify and plan to update geolocation records post-transfer.
8. Transfer Agreement Review
Ensure you have a proper transfer agreement that includes warranties, indemnification, and refund provisions. Use our Transfer Contract Generator to create a comprehensive agreement.
9. Escrow or Payment Protection
Never send full payment directly to a seller without escrow protection. Reputable platforms like IPv4.center hold funds in escrow and only release payment after the RIR confirms the transfer.
10. Seller Identity Verification
Verify the seller's identity and legitimacy:
- Cross-reference with RIR membership records
- Request proof of authorization to sell
- Check the seller's track record if using a marketplace
- Be wary of prices significantly below market rates
The Bottom Line
Taking time for due diligence protects your investment and prevents operational headaches after the transfer. At IPv4.center, we perform many of these checks automatically for all marketplace listings.
Start your search with confidence on our marketplace, where all listings are verified and reputation-checked.