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In another question, I found that Puppet was generating certificates for my machine's FQDN but not the simple host name. In that example, kungfumaster was the hostname and was the value retrieved by running hostname. Puppet was generating certificates which specified the FQDN kungfumaster.domain.com.

How did Puppet determine that this was my FQDN? I have tried all of the following and not seen anything matching *.domain.com:

$ hostname -a && hostname -d && hostname --domain && hostname -f &&  

    hostname --fqdn && hostname -A && hostname --long



kungfumaster

kungfumaster

kungfumaster 

kungfumaster

How can I get kungfumaster.domain.com from Bash? I've noticed that domain.com does in fact exist in /etc/resolv.conf, but I haven't been able to find it anywhere else.

I basically want to get the FQDN of the current machine as a string. The other solutions here on unix.se haven't worked for me. (ie: dnsdomainname, domainname, etc.)

It appears that under-the-hood, Puppet uses Facter to evaluate the domain names:

$ facter domain

domain.com

$ facter hostname

kungfumaster

$ facter fqdn

kungfumaster.domain.com

The answer is in the relevant Facter source code.

It does the following in order and uses the first one that appears to contain a domain name:

1. hostname -f


2. dnsdomainname


3. parsing resolv.conf for a "domain" or "search" entry

Probably because your system is part of a domain network that assigns a domain name. For example in my case, my router resolves all hostnames in the form of host.lan, "lan" being my domain, and "host" the name of my system.

The FQDN most likely comes from your router DNS, just run whatever you like of these commands:

nslookup your-ip-here

dig -x your-ip-here

host your-ip-here

An example using dig:

dig @10.0.0.1 -x 10.0.0.1



; <<>> DiG 9.9.5-4-Debian <<>> @10.0.0.1 -x 10.0.0.1

; (1 server found)

;; global options: +cmd

;; Got answer:

;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 11384

;; flags: qr aa rd ad; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; WARNING: recursion requested but not available



;; OPT PSEUDOSECTION:

; EDNS: version: 0, flags:; udp: 4096

;; QUESTION SECTION:

;1.0.0.10.in-addr.arpa.     IN  PTR



;; ADDITIONAL SECTION:

1.0.0.10.in-addr.arpa.  86400   IN  PTR dsldevice.lan.



;; Query time: 2181 msec

;; SERVER: 10.0.0.1#53(10.0.0.1)

;; WHEN: Thu Jun 19 20:01:32 AST 2014

;; MSG SIZE  rcvd: 77

Since I use my own DNS and not the router's I have to set the domain to query in the @ part. I'm querying the routers' own domain name.

You will find that it will return the domain name as your DNS/router sees you. There are various ways to disable this in the router, but I've found that the most easier way is just using other DNS.