host

Lookup A, AAAA, and MX records of a domain

$ host [domain]

$ host -t [field] [domain]

$ host [ip_address]

$ host [domain] [8.8.8.8]

host [-4|-6] [-aCdlLnrvwWx] [-c class] [-N ndots] [-R number] [-t type] [-T] [-W time] [name] [server]

-4
    Forces IPv4 query transport only

-6
    Forces IPv6 query transport only

-a
    Dumps all records (equivalent to -v -t ANY)

-c class
    Specifies query class (default IN)

-C
    Displays SOA records for a zone

-d level
    Sets debug level (0-1 typically)

-l
    Attempts zone transfer (AXFR)

-L size
    Sets EDNS0 buffer size

-N ndots
    Changes ndots value for absolute queries

-n
    Disables /etc/hosts lookup

-r
    Non-recursive queries

-R number
    Sets number of retries (default 5)

-s
    Strict mode: no UDP truncation handling

-t type
    Specifies RR type (A, MX, NS, TXT, ANY, etc.)

-T
    Uses TCP for queries instead of UDP

-v
    Enables verbose output

-w
    Waits forever for response

-W time
    Sets timeout in seconds (default 5)

-x
    Performs reverse (PTR) lookup

The host command is a lightweight, command-line DNS resolution tool used to query DNS servers for information about domain names, IP addresses, mail exchangers, name servers, and other resource records (RRs). It is ideal for quick DNS troubleshooting, verifying configurations, or scripting network diagnostics. By default, host performs recursive lookups for A and AAAA records, displaying results in a human-readable format with canonical names, aliases (CNAME), and IP addresses.

Key features include specifying record types (-t), querying custom servers, verbose output (-v or -a for all records), TCP mode (-T) for large responses, and options for recursion control (-r), retries (-R), and timeouts (-W). It supports IPv4/IPv6 selection and classes beyond IN (Internet). Unlike dig, output is concise without raw wire format, making it user-friendly for casual use. Part of BIND utilities, it relies on system resolvers unless overridden and warns on NXDOMAIN or SERVFAIL errors.

UDP default may truncate large responses; use -T. Zone transfers (-l) often blocked. Deprecated IPv6 reverse (-i) ignores ip6.arpa. Relies on resolver config; use full server for accuracy.

host example.com
Shows A/AAAA records.

host -t MX -v example.com
Verbose MX lookup.

host 8.8.8.8 ns1.example.com
Reverse PTR via specific server.

Results show hostname has address/IP, aliases via CNAME, auth servers, with TTL omitted. Errors: NXDOMAIN, SERVFAIL noted.

Developed by Paul Vixie for BIND 4.x in the 1990s as a simple nslookup alternative. Maintained by ISC in BIND 9+, with enhancements for IPv6, EDNS0, and modern DNSSEC. Widely distributed via bind-utils package since early Linux.

dig(1), nslookup(1), dnsdomainname(1), named-checkzone(8)