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DNS Lookup & SSL Certificate Checker - Network Diagnostic Tools

DNS Lookup SSL Checker IP Lookup

Troubleshooting network issues? Use these free online tools: DNS Lookup • SSL Checker • IP Lookup - No installation required!

Quick Access - Free Online Tools

Tool Purpose Link
DNS Lookup Query A, AAAA, MX, NS, TXT, SOA, CNAME records lookup
SSL Certificate Checker Verify SSL/TLS certificates, check expiration ssl
HTTP Headers Analyzer Analyze server headers, security, caching headers
IP Address Lookup Geolocation, ISP, VPN/proxy detection ip-lookup
Subnet Calculator Calculate CIDR, network ranges, subnet masks subnet
My IP Address View your public IP, location, ISP myip
Domain Age Checker Check domain registration age, WHOIS data domain-age
HTTP Status Checker Check website uptime, response codes http-status-checker

DNS Lookup - Command Line & Code Examples

Using dig (Most Powerful)

# Install dig
sudo apt-get install dnsutils  # Ubuntu/Debian
brew install bind              # macOS

# Query A record (IPv4)
dig example.com A +short
# 93.184.216.34

# Query AAAA record (IPv6)
dig example.com AAAA +short
# 2606:2800:220:1:248:1893:25c8:1946

# Query MX records (Mail servers)
dig example.com MX +short
# 10 mail.example.com.

# Query NS records (Name servers)
dig example.com NS +short
# ns1.example.com.
# ns2.example.com.

# Query TXT records (SPF, DKIM, verification)
dig example.com TXT +short
# "v=spf1 include:_spf.google.com ~all"

# Query all records
dig example.com ANY

# Trace DNS resolution path
dig +trace example.com

# Query specific DNS server
dig @8.8.8.8 example.com

# Reverse DNS lookup (IP to domain)
dig -x 93.184.216.34

Using nslookup

# Query A record
nslookup example.com

# Query specific record type
nslookup -type=MX example.com
nslookup -type=NS example.com
nslookup -type=TXT example.com

# Use specific DNS server
nslookup example.com 8.8.8.8

Using host

# Simple A record lookup
host example.com
# example.com has address 93.184.216.34

# Query MX records
host -t MX example.com

# Query all records
host -a example.com

# Reverse lookup
host 93.184.216.34

Python DNS Lookup

pip install dnspython
import dns.resolver

# Query A records
answers = dns.resolver.resolve('example.com', 'A')
for rdata in answers:
    print('IP:', rdata.address)

# Query MX records
mx_records = dns.resolver.resolve('example.com', 'MX')
for mx in mx_records:
    print(f'Mail server: {mx.exchange} (priority: {mx.preference})')

# Query TXT records
txt_records = dns.resolver.resolve('example.com', 'TXT')
for txt in txt_records:
    print('TXT:', txt.to_text())

# Query with specific nameserver
resolver = dns.resolver.Resolver()
resolver.nameservers = ['8.8.8.8', '8.8.4.4']
answers = resolver.resolve('example.com', 'A')

Node.js DNS Lookup

const dns = require('dns').promises;

// Query A records
async function lookupDNS(domain) {
  try {
    // A records (IPv4)
    const addresses = await dns.resolve4(domain);
    console.log('IPv4:', addresses);

    // AAAA records (IPv6)
    const ipv6 = await dns.resolve6(domain);
    console.log('IPv6:', ipv6);

    // MX records
    const mx = await dns.resolveMx(domain);
    console.log('MX:', mx);

    // TXT records
    const txt = await dns.resolveTxt(domain);
    console.log('TXT:', txt);

    // NS records
    const ns = await dns.resolveNs(domain);
    console.log('NS:', ns);

  } catch (err) {
    console.error('DNS lookup failed:', err);
  }
}

lookupDNS('example.com');

Or use the web tool: DNS Lookup Online

SSL Certificate Verification

Using openssl (Command Line)

# Check SSL certificate
openssl s_client -connect example.com:443 -servername example.com < /dev/null

# Show certificate details only
echo | openssl s_client -connect example.com:443 -servername example.com 2>/dev/null | openssl x509 -noout -text

# Check certificate expiration
echo | openssl s_client -connect example.com:443 -servername example.com 2>/dev/null | openssl x509 -noout -dates

# Get certificate chain
openssl s_client -showcerts -connect example.com:443 -servername example.com < /dev/null

# Check specific protocols
openssl s_client -tls1_2 -connect example.com:443
openssl s_client -tls1_3 -connect example.com:443

# Verify certificate with CA bundle
openssl s_client -connect example.com:443 -CAfile /etc/ssl/certs/ca-certificates.crt

Bash Script - SSL Expiry Checker

#!/bin/bash
# Check SSL certificate expiration

DOMAIN=$1

if [ -z "$DOMAIN" ]; then
    echo "Usage: $0 <domain>"
    exit 1
fi

# Get certificate expiry date
EXPIRY=$(echo | openssl s_client -connect $DOMAIN:443 -servername $DOMAIN 2>/dev/null | \
         openssl x509 -noout -enddate 2>/dev/null | cut -d= -f2)

if [ -z "$EXPIRY" ]; then
    echo "❌ Failed to retrieve certificate for $DOMAIN"
    exit 1
fi

# Convert to Unix timestamp
EXPIRY_TIMESTAMP=$(date -d "$EXPIRY" +%s)
CURRENT_TIMESTAMP=$(date +%s)

# Calculate days until expiry
DAYS_UNTIL_EXPIRY=$(( ($EXPIRY_TIMESTAMP - $CURRENT_TIMESTAMP) / 86400 ))

echo "Domain: $DOMAIN"
echo "Expires: $EXPIRY"
echo "Days until expiry: $DAYS_UNTIL_EXPIRY"

if [ $DAYS_UNTIL_EXPIRY -lt 0 ]; then
    echo "⚠️ EXPIRED!"
elif [ $DAYS_UNTIL_EXPIRY -lt 30 ]; then
    echo "⚠️ Expires soon! Renew within 30 days"
else
    echo "✅ Certificate is valid"
fi

Usage:

chmod +x ssl-check.sh
./ssl-check.sh example.com

Python SSL Checker

import ssl
import socket
from datetime import datetime

def check_ssl_expiry(hostname, port=443):
    context = ssl.create_default_context()

    with socket.create_connection((hostname, port)) as sock:
        with context.wrap_socket(sock, server_hostname=hostname) as ssock:
            cert = ssock.getpeercert()

            # Get expiry date
            not_after = cert['notAfter']
            expiry_date = datetime.strptime(not_after, '%b %d %H:%M:%S %Y %Z')

            # Calculate days until expiry
            days_until_expiry = (expiry_date - datetime.now()).days

            print(f"Domain: {hostname}")
            print(f"Issuer: {cert['issuer']}")
            print(f"Subject: {cert['subject']}")
            print(f"Expires: {expiry_date}")
            print(f"Days until expiry: {days_until_expiry}")

            if days_until_expiry < 0:
                print("⚠️ EXPIRED!")
            elif days_until_expiry < 30:
                print("⚠️ Expires soon!")
            else:
                print("✅ Certificate is valid")

# Usage
check_ssl_expiry('example.com')

Or use online tool: SSL Certificate Checker

Common DNS Record Types

Record Type Purpose Example
A IPv4 address example.com. 300 IN A 93.184.216.34
AAAA IPv6 address example.com. 300 IN AAAA 2606:2800:220:1:248:1893:25c8:1946
CNAME Canonical name (alias) www.example.com. IN CNAME example.com.
MX Mail exchange servers example.com. IN MX 10 mail.example.com.
TXT Text records (SPF, DKIM, verification) example.com. IN TXT "v=spf1 include:_spf.google.com ~all"
NS Name servers example.com. IN NS ns1.example.com.
SOA Start of authority Contains primary nameserver, admin email
PTR Reverse DNS (IP to domain) 34.216.184.93.in-addr.arpa. IN PTR example.com.
SRV Service locator Used for SIP, XMPP, LDAP services
CAA Certificate Authority Authorization Restrict which CAs can issue certificates

Look up any record type: DNS Lookup Tool

Troubleshooting Common DNS Issues

Issue 1: DNS Not Resolving

# Check if DNS is working
dig google.com +short

# If no response, try different DNS servers
dig @8.8.8.8 google.com     # Google DNS
dig @1.1.1.1 google.com     # Cloudflare DNS
dig @208.67.222.222 google.com  # OpenDNS

# Check local DNS cache
sudo systemd-resolve --flush-caches  # Linux
sudo killall -HUP mDNSResponder      # macOS
ipconfig /flushdns                   # Windows

Issue 2: Slow DNS Resolution

# Benchmark DNS servers
dig @8.8.8.8 google.com | grep "Query time"
dig @1.1.1.1 google.com | grep "Query time"

# Use fastest DNS server:
# Google: 8.8.8.8, 8.8.4.4
# Cloudflare: 1.1.1.1, 1.0.0.1
# OpenDNS: 208.67.222.222, 208.67.220.220

Issue 3: DNS Propagation Check

# Check if DNS has propagated globally
dig @8.8.8.8 example.com A       # Google (USA)
dig @1.1.1.1 example.com A       # Cloudflare (Global)
dig @ns1.yourdomain.com example.com A  # Your authoritative NS

# Different results = Still propagating (can take 24-48 hours)

Check propagation online: DNS Lookup Tool

Issue 4: Missing MX Records

# Check if email DNS is configured
dig example.com MX +short

# If empty, email won't work. Need to add MX records:
# Priority 10: mail.example.com
# Priority 20: mail2.example.com (backup)

Issue 5: SPF/DKIM Not Set Up

# Check SPF record (prevents email spoofing)
dig example.com TXT | grep "v=spf1"

# Check DKIM record
dig default._domainkey.example.com TXT

# If missing, email may go to spam

SSL/TLS Troubleshooting

Common SSL Errors & Fixes

Error Cause Fix
NET::ERR_CERT_DATE_INVALID Certificate expired Renew certificate (Let's Encrypt: 90 days)
NET::ERR_CERT_COMMON_NAME_INVALID Wrong domain in cert Regenerate for correct domain
NET::ERR_CERT_AUTHORITY_INVALID Self-signed or untrusted CA Use trusted CA (Let's Encrypt, DigiCert)
SSL_ERROR_NO_CYPHER_OVERLAP Weak/outdated ciphers Update server cipher suites
ERR_SSL_VERSION_OR_CIPHER_MISMATCH Old TLS version Enable TLS 1.2/1.3, disable TLS 1.0/1.1
ERR_SSL_PROTOCOL_ERROR Server misconfiguration Check Apache/Nginx SSL config

Test SSL configuration: SSL Certificate Checker

Check SSL Strength

# Test SSL/TLS versions supported
nmap --script ssl-enum-ciphers -p 443 example.com

# Check SSL Labs grade (A+ is best)
# Visit: https://www.ssllabs.com/ssltest/analyze.html?d=example.com

# Or use our tool:
# https://orbit2x.com/ssl

Network Diagnostic Scripts

Complete Network Diagnostic Tool (Bash)

#!/bin/bash
# Complete network diagnostic tool

DOMAIN=$1

if [ -z "$DOMAIN" ]; then
    echo "Usage: $0 <domain>"
    exit 1
fi

echo "========================================="
echo "Network Diagnostics for: $DOMAIN"
echo "========================================="

# 1. DNS Lookup
echo -e "\n[1] DNS LOOKUP"
echo "A records (IPv4):"
dig +short $DOMAIN A
echo "MX records (Mail):"
dig +short $DOMAIN MX
echo "NS records (Nameservers):"
dig +short $DOMAIN NS

# 2. Ping test
echo -e "\n[2] PING TEST"
ping -c 4 $DOMAIN

# 3. Traceroute
echo -e "\n[3] TRACEROUTE"
traceroute -m 15 $DOMAIN

# 4. HTTP Status
echo -e "\n[4] HTTP STATUS"
curl -I -s https://$DOMAIN | head -1

# 5. SSL Certificate
echo -e "\n[5] SSL CERTIFICATE"
echo | openssl s_client -connect $DOMAIN:443 -servername $DOMAIN 2>/dev/null | \
      openssl x509 -noout -dates -issuer -subject

# 6. Port Scan (common ports)
echo -e "\n[6] PORT SCAN"
nmap -F $DOMAIN

echo -e "\n========================================="
echo "Diagnostic complete!"
echo "========================================="

Best DNS Servers (2024)

Provider Primary Secondary Speed Privacy Filtering
Cloudflare 1.1.1.1 1.0.0.1 ⚡⚡⚡ Fastest ✅ No logging ❌ No
Google 8.8.8.8 8.8.4.4 ⚡⚡ Fast ⚠️ Logs queries ❌ No
Quad9 9.9.9.9 149.112.112.112 ⚡⚡ Fast ✅ No logging ✅ Malware blocking
OpenDNS 208.67.222.222 208.67.220.220 ⚡ Good ⚠️ Some logging ✅ Customizable
AdGuard 94.140.14.14 94.140.15.15 ⚡ Good ✅ No logging ✅ Ad blocking

Change DNS (Linux):

# Edit /etc/resolv.conf
sudo nano /etc/resolv.conf

# Add:
nameserver 1.1.1.1
nameserver 1.0.0.1

Change DNS (macOS):

# System Preferences → Network → Advanced → DNS
# Add: 1.1.1.1 and 1.0.0.1

Tools & Resources

Free Online Tools

Command Line Tools

  • dig - DNS lookup (most powerful)
  • nslookup - Simple DNS queries
  • host - Lightweight DNS tool
  • openssl - SSL/TLS testing
  • curl - HTTP client
  • nmap - Port scanning
  • traceroute - Network path tracing

Libraries

  • Node.js: dns module (built-in)
  • Python: dnspython, ssl module
  • Go: net package
  • PHP: dns_get_record()

FAQ

Q: Why is my DNS not updating?

A: DNS propagation takes 24-48 hours globally. Check with: DNS Lookup

Q: How do I check if my SSL certificate is valid?

A: Use SSL Certificate Checker - shows expiry, issuer, and errors

Q: What DNS server should I use?

A:

  • Fastest: Cloudflare (1.1.1.1)
  • Privacy: Quad9 (9.9.9.9) or Cloudflare
  • Ad-blocking: AdGuard (94.140.14.14)

Q: How often should I renew SSL certificates?

A: Let's Encrypt: 90 days. Paid certs: 1 year. Auto-renew recommended.

Q: Can I use free SSL certificates?

A: Yes! Let's Encrypt provides free, auto-renewable SSL certificates trusted by all browsers.

Related Tools

Made with ❤️ by Orbit2x - Free Network Diagnostic Tools

Try now: DNS Lookup • SSL Checker • IP Lookup

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DNS Lookup & SSL Certificate Checker - Network Diagnostic Tools

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