Host - Simple DNS Lookup Tool

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Overview

host is a simple DNS lookup utility that provides clean, easy-to-read output for DNS queries. It's designed to be more user-friendly than dig and more straightforward than nslookup, making it ideal for quick DNS lookups and basic troubleshooting tasks.

Basic Syntax

host [options] hostname [server]
host [options] IP_address [server]

Essential Commands

Basic DNS Lookups

# Look up A and AAAA records (IPv4 and IPv6)
host google.com

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# Reverse DNS lookup (IP to domain)
host 8.8.8.8

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# IPv6 reverse lookup
host 2001:4860:4860::8888

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# Using specific DNS server
host google.com 8.8.8.8

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Record Type Queries

# A record (IPv4 address)
host -t A google.com

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# AAAA record (IPv6 address)
host -t AAAA google.com

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# MX record (Mail Exchange)
host -t MX google.com

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# NS record (Name Server)
host -t NS google.com

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# TXT record (Text records)
host -t TXT google.com

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# CNAME record (Canonical Name)
host -t CNAME www.google.com

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# SOA record (Start of Authority)
host -t SOA google.com

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# PTR record (Pointer for reverse lookup)
host -t PTR 8.8.8.8

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# SRV record (Service record)
host -t SRV _sip._tcp.example.com

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Advanced Options

Verbose and Debug Output

# Verbose output (equivalent to -a)
host -v google.com

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# All records (ANY query type)
host -a google.com

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# Debug output
host -d google.com

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Timeout and Connection Options

# Set timeout (5 seconds)
host -W 5 google.com

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# Wait indefinitely for reply
host -w google.com

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# Use TCP instead of UDP
host -T google.com

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# Set number of UDP retries
host -R 3 google.com

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Query Behavior Options

# Non-recursive query
host -r google.com

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# Specify query class (default: IN)
host -c IN google.com

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# Show SOA records from all authoritative servers
host -C example.com

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# Zone transfer (list mode)
host -l example.com

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Popular DNS Servers

Using Different DNS Providers

# Google DNS
host google.com 8.8.8.8

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# Cloudflare DNS
host google.com 1.1.1.1

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# OpenDNS
host google.com 208.67.222.222

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# Quad9 DNS
host google.com 9.9.9.9

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Common Use Cases

Email Server Troubleshooting

# Check MX records for email routing
host -t MX example.com

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# Verify mail server IP
host mail.example.com

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# Check multiple mail servers
host -t MX gmail.com yahoo.com outlook.com

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Domain Verification

# Check TXT records for domain verification
host -t TXT example.com

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# Verify SPF records
host -t TXT example.com|grep "v=spf1"

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# Check DKIM records
host -t TXT default._domainkey.example.com

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Network Diagnostics

# Check authoritative name servers
host -t NS example.com

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# Verify domain authority information
host -t SOA example.com

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# Check CNAME aliases
host -t CNAME www.example.com

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# Comprehensive domain analysis
host -a example.com

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Reverse DNS Lookups

# Check hostname for IP
host 192.168.1.1

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# Verify server identity
host 208.67.222.222

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# IPv6 reverse lookup
host 2001:4860:4860::8844

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Troubleshooting Commands

Debug and Verbose Queries

# Debug mode with specific record type
host -d -t A google.com

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# Verbose TCP query
host -v -T google.com

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# Non-recursive NS query
host -r -t NS google.com

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# Extended timeout with MX query
host -W 10 -t MX example.com

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Command Options Reference

Option	Description
-a	Equivalent to -v and -t ANY
-C	Show SOA records from all authoritative servers
-c class	Specify query class (default: IN)
-d	Enable debug output
-l	List mode (zone transfer)
-n	Use IP6.INT domain for IPv6 reverse lookups
-N ndots	Set number of dots for absolute names
-r	Make non-recursive queries
-R retries	Set number of UDP retries
-t type	Specify query type (A, AAAA, MX, NS, etc.)
-T	Use TCP connection
-v	Verbose output
-W seconds	Set timeout in seconds
-w	Wait indefinitely for reply

Record Types

Type	Description	Example
A	IPv4 address	host -t A google.com
AAAA	IPv6 address	host -t AAAA google.com
CNAME	Canonical name	host -t CNAME www.google.com
MX	Mail exchange	host -t MX google.com
NS	Name server	host -t NS google.com
PTR	Pointer (reverse)	host -t PTR 8.8.8.8
SOA	Start of authority	host -t SOA google.com
SRV	Service record	host -t SRV _sip._tcp.example.com
TXT	Text record	host -t TXT google.com
ANY	All records	host -a google.com

Installation

Linux (Ubuntu/Debian)

sudo apt-get install dnsutils

Linux (CentOS/RHEL/Fedora)

sudo yum install bind-utils
# or
sudo dnf install bind-utils

macOS

host comes pre-installed with macOS.

Windows

Use Windows Subsystem for Linux (WSL) or install via package managers like Chocolatey.

Tips and Best Practices

1. Clean output: host provides cleaner, more readable output than dig
2. Quick lookups: Ideal for simple DNS queries and basic troubleshooting
3. Multiple queries: Can query multiple domains in a single command
4. Reverse lookups: Automatically detects IP addresses and performs reverse lookups
5. Timeout settings: Use -W option for slow or unreliable networks
6. TCP queries: Use -T for large responses or when UDP is blocked
7. Combine with other tools: Use alongside dig and nslookup for comprehensive analysis

Common Error Messages

Error	Meaning
Host not found	Domain doesn't exist (NXDOMAIN)
No address associated with hostname	No A/AAAA records found
Connection timed out	DNS server unreachable
Server failure	DNS server error (SERVFAIL)
Query refused	DNS server refused the query

Related Commands

• dig - More detailed DNS lookup tool with extensive options
• nslookup - Interactive DNS lookup utility
• ping - Test network connectivity and resolve hostnames
• traceroute - Trace network path to destination
• whois - Domain registration and ownership information