dns domain name servers /etc/resolv.conf

• Escenario: no resuelve una url, por ejemplo “https://www.intercash.net”

wget https://www.intercash.net
--07:19:41--  https://www.intercash.net/
           => `index.html'
Resolving www.intercash.net... failed: Temporary failure in name resolution.

1) Preguntamos quien es el servidor adecuado para preguntar por un objeto determinado (OJO, usamos solo el dominio, sin CNAME):

whois intercash.net

[Querying whois.internic.net]
[Redirected to whois.register.com]
[Querying whois.register.com]
[whois.register.com]

The data in Register.com's WHOIS database is provided to you by
Register.com for information purposes only, that is, to assist you in
obtaining information about or related to a domain name registration
record.  Register.com makes this information available "as is," and
does not guarantee its accuracy.  By submitting a WHOIS query, you
agree that you will use this data only for lawful purposes and that,
under no circumstances will you use this data to: (1) allow, enable,
or otherwise support the transmission of mass unsolicited, commercial
advertising or solicitations via direct mail, electronic mail, or by
telephone; or (2) enable high volume, automated, electronic processes
that apply to Register.com (or its systems).  The compilation,
repackaging, dissemination or other use of this data is expressly
prohibited without the prior written consent of Register.com.
Register.com reserves the right to modify these terms at any time.
By submitting this query, you agree to abide by these terms.


   Registrant:
      o.b.l. computer network Ltd
      alon elbaz
      6 ginzburg street
      rishon le zion,   75707
      IL
      Phone: 962-9098
      Email: alon@compunet.co.il


   Registrar Name....: Register.com
   Registrar Whois...: whois.register.com
   Registrar Homepage: www.register.com

   Domain Name: intercash.net
      Created on..............: 2002-02-17
      Expires on..............: 2012-02-17

   Administrative Contact:
      o.b.l. computer network Ltd
      alon elbaz
      153 byalik street
      Ramat Gan,   52523
      IL
      Phone: 612-6966
      Email: alon@netpay.co.il


   Technical  Contact:
      Register.Com
      Domain Registrar
      575 8th Avenue 11th Floor
      New York, NY 10018
      US
      Phone: 1-902-7492701
      Email: domain-registrar@register.com


   DNS Servers:
      ns.servnet.co.il
      ns01.servnet.co.il
      dns.netpay.co.il


Visit AboutUs.org for more information about intercash.net

<A HREF="http://www.aboutus.org/intercash.net">AboutUs: intercash.net</A>

Register your domain name at http://www.register.com

2) Intentamos resolver el nombre con el servidor de nombres autorizado:

host www.intercash.net ns.servnet.co.il

Using domain server:
Name: ns.servnet.co.il
Address: 84.94.231.9#53
Aliases: 

www.intercash.net has address 80.179.180.57

Podriamos seguir probando con 'ns01.servnet.co.il' y 'dns.netpay.co.il'

3) Vemos los servidores de nombre locales:

cat /etc/resolv.conf

search midominio.com
nameserver 10.10.30.31
nameserver 10.10.30.21

4) Forzamos la busqueda con uno y otro:

host www.intercash.net 10.10.30.31
host www.intercash.net 10.10.30.21

En mi caso volvio a resolver bien justo en este momento, por lo que el fallo de resolucion apenas duro 2 minutos

El servidor DNS que asigna el DHCP lo podemos encontrar en los ficheros del directorio /var/lib/dhcp/ Por ejemplo:

dhclient-0a276062-9d51-445c-b56d-bfa92623fca1-eth0.lease

Pero el actual es

dhclient.leases

lease {
  interface "eth0";
  fixed-address 10.7.1.26;
  option subnet-mask 255.255.255.0;
  option routers 10.7.1.236;
  option dhcp-lease-time 172800;
  option dhcp-message-type 5;
  option domain-name-servers 10.7.1.49;
  option dhcp-server-identifier 10.7.1.49;
  option dhcp-renewal-time 86400;
  option dhcp-rebinding-time 151200;
  option domain-name "avanttic.local";
  renew 2 2013/05/14 13:10:31;
  rebind 3 2013/05/15 08:06:56;
  expire 3 2013/05/15 14:06:56;
}