resolv.conf vs arquivo base

Question

Aqui está o meu arquivo base

root@iracavcsdbc03:~# cat /etc/resolvconf/resolv.conf.d/base
nameserver 1.1.1.1
nameserver 2.2.2.2
nameserver 3.3.3.3
nameserver 4.4.4.4

Depois de executar resolvconf -u , por que o novo arquivo resolv.conf gerado mostra apenas 3 IPs nem todos 4, como mencionado no arquivo base?

root@iracavcsdbc03:~# cat /etc/resolv.conf
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
#     DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
#
# Modify /etc/resolvconf/resolv.conf.d/base to make changes permanent!
#
nameserver 1.1.1.1
nameserver 2.2.2.2
nameserver 3.3.3.3
search infra.aic.att.net
options attempts:2
options timeout:3

    

Answer 1

O script de atualização para o resolvconf grava até três linhas de servidores de nomes para resolv.conf.

Se você acessar man pages para resolvconf , poderá encontrar essas informações:

$ man resolvconf

Vá para a linha 47 ou libc da seção CONSUMERS OF NAMESERVER INFORMATION e observe o item número 1 :

   libc
       The most important software package that  subscribes  to  the  notification  service  is  the  GNU  C  Library
       resolver(3).   This  library  is used by many applications that need to resolve domain names.  When nameserver
       information is updated, the script /etc/resolvconf/update.d/libc generates a new version of the resolver  con‐
       figuration file, /run/resolvconf/resolv.conf, as described below.  If the new version of the file differs from
       the previously generated one then the hook scripts found in /etc/resolvconf/update-libc.d/ are executed.

       The dynamically generated resolver  configuration  file  always  starts  with  the  contents  of  /etc/resolv‐
       conf/resolv.conf.d/head  and  ends  with the contents of /etc/resolvconf/resolv.conf.d/tail.  Between head and
       tail the libc script inserts dynamic nameserver information compiled from,  first,  information  provided  for
       configured  interfaces;  second, static information from /etc/resolvconf/resolv.conf.d/base.  Specifically, it
       writes:

         1) up to three nameserver lines, ordered according to /etc/resolvconf/interface-order, possibly fewer if one
            of  the  addresses is a loopback address and the TRUNCATE_NAMESERVER_LIST_AFTER_LOOPBACK_ADDRESS environ‐
            ment variable is affirmatively set, as discussed in the ENVIRONMENT VARIABLES section;

         2) up to one search line containing the combined domain search list from all  "domain"  and  "search"  input
            lines, also ordered according to interface-order(5);

         3) all other non-comment input lines.