SPF Checker Tools vs Manual DNS Lookups

If you're technical, you might wonder: why use an SPF checker tool when I can just run dig or nslookup?

Manual DNS lookups work. But dedicated SPF tools catch things that raw DNS queries miss. Here's the comparison.

Quick Comparison

The Manual Approach

Checking SPF with dig:

dig +short TXT example.com | grep spf

Output:

"v=spf1 include:_spf.google.com include:sendgrid.net ~all"

This tells you what the SPF record contains. But it doesn't tell you:

• Whether the syntax is valid
• How many DNS lookups it triggers
• Whether nested includes have problems
• If you're close to the 10-lookup limit

To get that information manually, you need to:

1. Query the main SPF record
2. Query each include domain
3. Query nested includes within those
4. Count total lookups
5. Visually inspect for syntax errors

For a complex SPF record, this takes 10-15 minutes of careful work.

What SPF Checker Tools Add

An SPF checker does all of the above automatically:

Automatic lookup counting

The most critical SPF limitation is the 10 DNS lookup limit. Manual counting is tedious:

• include:_spf.google.com → 1 lookup, but Google's record has nested includes (3-4 more)
• include:sendgrid.net → 1 lookup, plus any nested includes
• mx → 1 lookup, plus lookups for each MX server's A record

An SPF checker recursively resolves everything and gives you a total.

Syntax validation

SPF syntax errors aren't always obvious:

v=spf1 inclde:_spf.google.com ~all

Spot the error? It's inclde instead of include. A tool catches this instantly. Manual inspection might miss it.

Multiple record detection

Having two SPF records is a common mistake:

dig +short TXT example.com

Output:

"v=spf1 include:_spf.google.com ~all"
"v=spf1 include:sendgrid.net ~all"

Easy to miss when you're quickly checking. SPF tools flag this immediately.

Nested problem detection

If one of your includes points to a record with errors, manual checking won't catch it unless you query every nested record.

Tools recursively validate the entire chain.

When Manual Lookups Make Sense

There are times when dig or nslookup is the right choice:

Quick existence check — Just need to confirm an SPF record exists? dig +short TXT domain.com is fast.

Debugging DNS propagation — Querying specific DNS servers to check propagation status.

Offline or restricted environments — When you can't access web tools.

Learning — Understanding how SPF works by manually tracing the resolution.

When to Use a Tool

For anything beyond "does this record exist," a tool saves time and catches more issues:

• Validating before making DNS changes
• Checking lookup counts before adding a new service
• Auditing multiple domains
• Troubleshooting deliverability problems
• Sharing results with non-technical team members

The Time Comparison

Scenario: Check SPF for 5 domains and count their DNS lookups.

Manual approach:

• Query each domain: 5 × 30 seconds = 2.5 minutes
• Query includes: 5 × 3 includes × 30 seconds = 7.5 minutes
• Count and tally: 5 minutes
• Total: ~15 minutes

Tool approach:

• Enter 5 domains: 5 × 10 seconds = 50 seconds
• Total: under 1 minute

The difference compounds when you're checking more domains or need to do this regularly.

Combining Both Approaches

Many professionals use both:

• SPF tools for validation, auditing, and getting a quick overview
• dig/nslookup for debugging specific DNS issues, checking propagation, or scripting

They're complementary, not mutually exclusive.

Beyond One-Time Checks

Whether you use tools or manual queries, both are point-in-time checks. For ongoing monitoring, you need automation that:

• Checks regularly (daily or more)
• Alerts when records change
• Notifies you of new errors