DNS Lookup API: A Developer's Guide to Programmatic DNS Queries

DNS records are the backbone of internet infrastructure, but querying them programmatically is surprisingly tedious. You need dig or nslookup for ad-hoc checks, a DNS resolver library for code, and separate calls for each record type. A DNS Lookup API collapses all of that into a single HTTP request that returns structured JSON.

Why developers need a DNS API

Common use cases where programmatic DNS lookup beats manual tools:

Email validation pipelines: Check MX records to verify a domain can receive mail before sending. A domain without MX records will bounce.
Security research: Enumerate TXT records for SPF, DKIM, and DMARC policies. Check NS records to map infrastructure. Resolve CNAME chains to detect domain spoofing.
Infrastructure monitoring: Track SOA serial numbers across nameservers to detect propagation delays. Verify SRV records for service discovery.
Certificate management: CAA records control which certificate authorities are allowed to issue certificates for a domain. Querying them programmatically helps automate certificate workflows.

Querying all record types in one call

The traditional approach requires separate calls per record type:

dig +short MX github.com
dig +short TXT github.com
dig +short NS github.com

A unified DNS API returns everything in one structured response:

curl -X POST "https://theglitchstore.com/api/secure-proxy?api=dns-lookup" \
  -H "x-api-key: gstore_YOUR_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "domain": "github.com",
    "types": ["A", "AAAA", "MX", "NS", "TXT", "CAA"]
  }'

The response is structured JSON with each record type as a key:

{
  "domain": "github.com",
  "records": {
    "A": ["20.205.243.166"],
    "MX": [{"priority": 0, "exchange": "smtp.github.com."}],
    "NS": ["ns-1707.awsdns-21.co.uk.", "ns-421.awsdns-52.com."],
    "TXT": ["\"v=spf1 include:spf.github.com -all\""],
    "CAA": [{"flag": 0, "tag": "issue", "value": "digicert.com"}]
  }
}

Record types explained

Type	What it returns	Why developers query it
A	IPv4 address	Resolve a domain to its server
AAAA	IPv6 address	IPv6 connectivity checks
MX	Mail exchange servers	Verify email deliverability
NS	Authoritative nameservers	Infrastructure mapping
TXT	Arbitrary text records	SPF, DKIM, DMARC, domain verification
CNAME	Canonical name	Redirect chains, alias resolution
SOA	Start of authority	Zone serial, refresh intervals
SRV	Service records	Service discovery (SIP, XMPP, AD)
CAA	Certification authority	Which CAs can issue certs
PTR	Reverse DNS	IP-to-hostname verification

Practical example: email deliverability check

Before adding an email address to your database, verify the domain has valid MX records:

async function canReceiveEmail(email) {
  const domain = email.split('@')[1];
  const res = await fetch('https://theglitchstore.com/api/secure-proxy?api=dns-lookup', {
    method: 'POST',
    headers: {
      'x-api-key': process.env.GLITCH_STORE_KEY,
      'Content-Type': 'application/json',
    },
    body: JSON.stringify({ domain, types: ['MX', 'TXT'] }),
  });
  const data = await res.json();
  const hasMX = data.records.MX && data.records.MX.length > 0;
  const spf = data.records.TXT?.find(t => t.includes('v=spf1'));
  return { canReceive: hasMX, hasSpf: Boolean(spf) };
}

This catches domains that will silently bounce and flags those without SPF records (more likely to be flagged as spam).

Pricing

DNS lookups cost 0.5 credits per call ($0.005). At 1 credit = $0.01, 100 credits costs $1 and covers 200 DNS queries across all record types. Credits never expire.