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NAME¶

hostname — show or set the system’s host name
domainname — show or set the system’s NIS/YP domain name
ypdomainname — show or set the system’s NIS/YP domain name
nisdomainname — show or set the system’s NIS/YP domain name
dnsdomainname — show the system’s DNS domain name

SYNOPSIS¶

hostname [-a|—alias] [-d|—domain] [-f|—fqdn|—long] [-A|—all-fqdns] [-i|—ip-address] [-I|—all-ip-addresses] [-s|—short] [-y|—yp|—nis]
hostname [-b|—boot] [-F|—file filename] [hostname]
hostname [-h|—help] [-V|—version]

domainname [nisdomain] [-F file]
ypdomainname [nisdomain] [-F file]
nisdomainname [nisdomain] [-F file]

DESCRIPTION¶

Hostname is used to display the system’s DNS name, and to display or set its hostname or NIS domain name.

GET NAME¶

hostname will print the name of the system as returned by the gethostname(2) function.

domainname will print the NIS domainname of the system. domainname uses the gethostname(2) function, while ypdomainname and nisdomainname use the getdomainname(2).

dnsdomainname will print the domain part of the FQDN (Fully Qualified Domain Name). The complete FQDN of the system is returned with hostname —fqdn (but see the warnings in section THE FQDN below).

SET NAME¶

When called with one argument or with the —file option, the commands set the host name or the NIS/YP domain name. hostname uses the sethostname(2) function, while all of the three domainname, ypdomainname and nisdomainname use setdomainname(2). Note, that this is effective only until the next reboot. Edit /etc/hostname for permanent change.

Note, that only the super-user can change the names.

It is not possible to set the FQDN or the DNS domain name with the dnsdomainname command (see THE FQDN below).

The host name is usually set once at system startup in /etc/init.d/hostname.sh (normally by reading the contents of a file which contains the host name, e.g. /etc/hostname).

THE FQDN¶

The FQDN (Fully Qualified Domain Name) of the system is the name that the resolver(3) returns for the host name, such as, ursula.example.com. It is usually the hostname followed by the DNS domain name (the part after the first dot). You can check the FQDN using hostname —fqdn or the domain name using dnsdomainname.

You cannot change the FQDN with hostname or dnsdomainname.

The recommended method of setting the FQDN is to make the hostname be an alias for the fully qualified name using /etc/hosts, DNS, or NIS. For example, if the hostname was «ursula», one might have a line in /etc/hosts which reads

Technically: The FQDN is the name getaddrinfo(3) returns for the host name returned by gethostname(2). The DNS domain name is the part after the first dot.

Therefore it depends on the configuration of the resolver (usually in /etc/host.conf) how you can change it. Usually the hosts file is parsed before DNS or NIS, so it is most common to change the FQDN in /etc/hosts.

If a machine has multiple network interfaces/addresses or is used in a mobile environment, then it may either have multiple FQDNs/domain names or none at all. Therefore avoid using hostname —fqdn, hostname —domain and dnsdomainname. hostname —ip-address is subject to the same limitations so it should be avoided as well.

OPTIONS¶

-a, —alias Display the alias name of the host (if used). This option is deprecated and should not be used anymore. -A, —all-fqdns Displays all FQDNs of the machine. This option enumerates all configured network addresses on all configured network interfaces, and translates them to DNS domain names. Addresses that cannot be translated (i.e. because they do not have an appropriate reverse IP entry) are skipped. Note that different addresses may resolve to the same name, therefore the output may contain duplicate entries. Do not make any assumptions about the order of the output. -b, —boot Always set a hostname; this allows the file specified by -F to be non-existant or empty, in which case the default hostname localhost will be used if none is yet set. -d, —domain Display the name of the DNS domain. Don’t use the command domainname to get the DNS domain name because it will show the NIS domain name and not the DNS domain name. Use dnsdomainname instead. See the warnings in section THE FQDN above, and avoid using this option. -f, —fqdn, —long Display the FQDN (Fully Qualified Domain Name). A FQDN consists of a short host name and the DNS domain name. Unless you are using bind or NIS for host lookups you can change the FQDN and the DNS domain name (which is part of the FQDN) in the /etc/hosts file. See the warnings in section THE FQDN above und use hostname —all-fqdns instead wherever possible. -F, —file filename Read the host name from the specified file. Comments (lines starting with a `#’) are ignored. -i, —ip-address Display the network address(es) of the host name. Note that this works only if the host name can be resolved. Avoid using this option; use hostname —all-ip-addresses instead. -I, —all-ip-addresses Display all network addresses of the host. This option enumerates all configured addresses on all network interfaces. The loopback interface and IPv6 link-local addresses are omitted. Contrary to option -i, this option does not depend on name resolution. Do not make any assumptions about the order of the output. -s, —short Display the short host name. This is the host name cut at the first dot. -V, —version Print version information on standard output and exit successfully. -y, —yp, —nis Display the NIS domain name. If a parameter is given (or —file name ) then root can also set a new NIS domain. -h, —help Print a usage message and exit.

NOTES¶

The address families hostname tries when looking up the FQDN, aliases and network addresses of the host are determined by the configuration of your resolver. For instance, on GNU Libc systems, the resolver can be instructed to try IPv6 lookups first by using the inet6 option in /etc/resolv.conf.

FILES¶

/etc/hostname Historically this file was supposed to only contain the hostname and not the full canonical FQDN. Nowadays most software is able to cope with a full FQDN here. This file is read at boot time by the system initialization scripts to set the hostname.

/etc/hosts Usually, this is where one sets the domain name by aliasing the host name to the FQDN.

AUTHORS¶

Source file:	domainname.1.en.gz (from hostname 3.18+b1)
Source last updated:	2016-07-03T19:26:17Z
Converted to HTML:	2019-06-03T08:14:38Z

Источник

How to get a hostname/domain name from an IP address in Linux

One of the questions that many Linux users ask is how they can retrieve a system’s hostname using its IP address. It may seem an uphill task, but in the real sense, it’s quite easy. Essentially, this is known as the reverse DNS lookup. Reverse DNS lookup queries an IP address to retrieve the hostname or domain of the server. The exact opposite is the Forward DNS lookup which maps the domain name to the IP address.

In this short guide, we have explored a few ways to performs Reverse DNS lookup and get a domain name from an IP address. For demonstration purposes, I have used Ubuntu 20.04.

Prerequisites

Before you roll up your sleeves, ensure that your remote host has an A record which is a DNS entry that points or maps a domain name to an IP address

Perform DNS Reverse lookup using dig command

Dig command is a flexible and powerful tool that is used for querying or probing DNS records. It’s an acronym for domain information groper and allows you to retrieve a wide array of DNS information such as A, CNAME, MX, and SOA records.

Perform DNS Reverse lookup using nslookup command

A nslookup command is a troubleshooting tool that features highly in a sysadmin’s armory. It’s a versatile tool that performs all DNS record querying such as CNAME, A, MX, and reverses or PTR records.

To retrieve a domain name from an IP address, use the command syntax:

Perform DNS Reverse lookup using the host command

Similarly, you can use the host command to obtain a hostname or domain name from an IP address using the syntax as shown.

For example, to check the domain name for the IP 5.9.235.235, execute the command:

Just like the Nslookup command, you can also use the host command with hostnames or IP addresses.

Conclusion

The few examples that we have just elaborated are a sure way of helping you obtain the domain name from an IP address. Usually, the reverse DNS lookup is trivial and not as crucial as the forward lookup, which maps domain names to IP addresses. Your feedback or contribution will be highly welcomed.

About the author

Karim Buzdar

Karim Buzdar holds a degree in telecommunication engineering and holds several sysadmin certifications. As an IT engineer and technical author, he writes for various web sites. He blogs at LinuxWays.

Источник

How to find the domain name of a server?

I’m having trouble finding the domain name of my school’s server, I read another question similar to this but their commands didn’t work. I tried to use nslookup and then when I was prompted I entered server . I get the following output. I don’t understand where the domain name is stored. I’m using a wired LAN connection from my university.

Default Server: 127.0.01 Address: 127.0.0.1#53 Default Server: ::1 Address: ::1#53 

please would you clarify [. ] and then when I was prompted I entered server , you do know the server ip right? thx

3 Answers 3

You should nslookup the IP. It will return. Example.

[nazu@healer ~]$ nslookup > bro-ns-01 Server: 10.100.1.2 Address: 10.100.1.2#53 Name: bro-ns-01.angelsofclockwork.net Address: 10.100.1.2 > 10.100.1.2 Server: 10.100.1.2 Address: 10.100.1.2#53 2.1.100.10.in-addr.arpa name = bro-ns-01.angelsofclockwork.net. > 

I’m assuming you’re using dnsmasq or otherwise, because your server address is set to your localhost. If that’s the case, it should still be transparent enough to pull the information.

You could also look at /etc/resolve.conf if you’re on the same network. You’re more than likely being given a reverse DNS entry that has the same domain suffix of static servers.

[nazu@healer ~]$ cat /etc/resolv.conf ; generated by /usr/sbin/dhclient-script search angelsofclockwork.net. nameserver 10.100.1.2 

Источник

How To Get Host Name and Domain Name Of Linux?

Host name is the identifier of a system in the network. Host name can be get with different ways in Linux. Host name is generally put in the /etc/hostname file.

Get Host name By Echoing Host name File

Host name information is stored in a file /etc/hostname . So we can simple print the host name to the terminal with echo command like below.

Get Host name With hostname Command

We can get host name with hostname command. This will only list host name and will not print domain related information.

Get Fully Qualified Host name

We can get fully qualified host name which provides full name with domain information.

Hostname File

Host name file /etc/hostname will only provide host name with fully qualified domain name. There will any no other data in this file.

Change Host name

As the hostname is stored in the /etc/hostname file we can change the hostname by editing this file. We will set the hostname as ubu1 with the following echo command. Keep in mind that in order to change /etc/hostname file we require root privileges which can be get with the sudo command.

$ sudo echo "ubu1" > /etc/hostname

Get Domain Name

Domain name information is about the systems network configuration.

How To Get Host Name and Domain Name Of Linux? Infografic

Источник