1.\" (c) Magerya Vitaly 2.\" 3.\" Copying and distribution of this file, with or without modification, 4.\" are permitted in any medium without royalty provided the copyright 5.\" notice and this notice are preserved. This file is offered as-is, 6.\" without any warranty. 7.Dd Aug 27, 2012 8.Dt LDNS-HOST 1 9.Os 10.Sh NAME 11.Nm ldns-host 12.Nd DNS lookup utility 13.Sh SYNOPSIS 14.Nm 15.Op Fl aCdilrsTvw46 16.Op Fl c Ar class 17.Op Fl N Ar ndots 18.Op Fl R Ar number 19.Op Fl t Ar type 20.Op Fl W Ar wait 21.Ar name 22.Op Ar server 23.Sh DESCRIPTION 24.Nm 25is a simple utility for performing DNS lookups. It is normally 26used to convert names to IP addresses and vice versa. 27.Pp 28.Ar name 29is the domain name that is to be looked up. It can also be a 30dotted-decimal IPv4 address or a colon-delimited IPv6 address, 31in which case 32.Nm 33will by default perform a reverse lookup for that address. 34.Pp 35When 36.Ar name 37is not provided, 38.Nm 39prints a short summary of it's usage. 40.Pp 41.Ar server 42is an optional argument which is either a domain name or an IP 43address of the name server that 44.Nm 45should query instead of the server or servers listed in 46.Pa /etc/resolv.conf . 47When 48.Ar server 49is a domain name, system resolver is used to obtain it's address. 50.Pp 51Supported options: 52.Bl -tag -width indent 53.It Fl a 54Make a verbose query of type 55.Cm ANY . 56Equivalent to 57.Fl v Fl t Cm ANY . 58.It Fl C 59Query for 60.Cm SOA 61records for zone 62.Ar name 63from all of it's authoritative name servers. The list of name 64servers is obtained via 65.Cm NS 66query for 67.Ar name . 68.It Fl c Ar class 69Perform DNS query of class 70.Ar class . 71Recognized classes are 72.Cm IN Pq Internet , 73.Cm CH Pq Chaosnet , 74.Cm HS Pq Hesiod , 75.Cm NONE , 76.Cm ANY 77and 78.Cm CLASS Ns Ar N 79(where 80.Ar N 81is a number from 1 to 255). Default is 82.Cm IN . 83.It Fl d 84Produce verbose output. This is a synonym for 85.Fl v , 86and is provided for backward compatibility. 87.It Fl i 88Use IP6.INT domain for reverse lookups of IPv6 addresses (as 89defined in RFC1886; note that RFC4159 deprecates IP6.INT). 90By default IP6.ARPA is used. 91.It Fl l 92List all 93.Cm NS, PTR, A 94and 95.Cm AAAA 96records in zone 97.Ar name 98by performing a zone transfer 99.Pq Cm AXFR . 100You can combine this option with 101.Fl a 102to print all records, or with 103.Fl t 104to only print specific ones. 105.It Fl N Ar ndots 106Consider names with at least this many dots as absolute. That 107is, try to resolve them directly before consulting 108.Ic domain 109or 110.Ic search 111options from 112.Pa /etc/resolv.conf . 113.It Fl r 114Perform non-recursive query to the name server by clearing RD 115.Pq Dq recursion desired 116bit of the query. 117.It Fl R Ar number 118Retry this many times when a query does not receive an answer 119in time. The default is 1 retry. If 120.Ar number 121is negative or zero, 1 is used instead. 122.It Fl s 123Report SERVFAIL responses as they are, do not ignore them. 124.It Fl T 125Query name server over TCP. By default UDP is used, except for 126.Cm AXFR 127and 128.Cm IXFR 129queries, which require TCP. 130.Nm 131will also retry UDP queries in TCP mode if the UDP response was 132truncated (i.e. had TC bit set). 133.It Fl t Ar type 134Perform DNS query of type 135.Ar type , 136which can be any standard query type name 137.Pq Cm A , CNAME , MX , TXT , No etc , 138a wildcard query 139.Pq Cm ANY , 140or 141.Cm TYPE Ns Ar N , 142where 143.Ar N 144is a number from 1 to 65535. For 145.Cm IXFR Pq incremental zone transfer 146queries the starting serial number can be specified by appending 147an equal sign followed by the number 148.Pq e.g. Fl t Cm IXFR Ns =12345678 . 149.Pp 150The default is to query for 151.Cm A , AAAA , No and Cm MX 152records, unless 153.Fl C 154or 155.Fl l 156options are given (in which case 157.Cm SOA 158or 159.Cm AXFR 160queries are made) or 161.Ar name 162is a valid IP address 163(in which case reverse lookup using 164.Cm PTR 165query is performed). 166.It Fl v 167Produce verbose output. 168.It Fl w 169Wait forever (or for a very long time) for response from the 170name server. 171.It Fl W Ar wait 172Wait this many seconds for a reply from name server before timing 173out. If 174.Ar wait 175is negative or zero, value of 1 is used. The default is to wait 17610 seconds for TCP connections, and 5 seconds for UDP (both are 177subject to retries, see option 178.Fl R ) . 179.It Fl 4 180Only use IPv4 transport. 181.It Fl 6 182Only use IPv6 transport. 183.El 184.Sh FILES 185.Pa /etc/resolv.conf 186.Sh SEE ALSO 187.Xr drill 1 , 188.Xr resolv.conf 5 189.Sh COMPATIBILITY 190.Nm 191aims to be reasonably compatible with 192.Sq host 193utility from BIND9 distribution, both in supported options and 194in produced output. Here is a list of known notable differences: 195.Bl -bullet 196.It 197Debugging options 198.Pq Fl D No and Fl m 199are not supported. 200.It 201Query class 202.Cm CLASS0 203and type 204.Cm TYPE0 205are not supported. 206.It 207Backslashes in domain names are treated especially. 208.It 209The maximum of 255 retries (option 210.Fl R ) 211are supported. 212.It 213Some resource records are formatted differently. For example, 214.Cm RRSIG 215and 216.Cm DNSKEY 217records are displayed without spaces in them. 218.It 219When parsing 220.Pa /etc/resolv.conf 221commands 222.Ic sortlist 223and 224.Ic options 225are ignored. When multiple 226.Ic search 227and/or 228.Ic domain 229commands are present, 230.Nm 231first uses the last 232.Ic domain 233command, and then all of 234.Ic search 235commands, while 236.Sq host 237from BIND9 uses whatever command was specified last. 238.It 239.Sq Pseudosection TSIG 240is missing from verbose packet output. 241.El 242.Sh AUTHORS 243.An Vitaly Magerya Aq magv@tx97.net 244