O problema foi resolvido depois de remover o comando:
porta de origem da consulta 53;
Por algum motivo, não consigo consultar domínios específicos.
Embora dig funcione como deveria, nslookup não funciona.
home1:/# dig +trace www.capital.gr
; <<>> DiG 9.7.3 <<>> +trace www.capital.gr
;; global options: +cmd
. 514903 IN NS h.root-servers.net.
. 514903 IN NS a.root-servers.net.
. 514903 IN NS m.root-servers.net.
. 514903 IN NS j.root-servers.net.
. 514903 IN NS i.root-servers.net.
. 514903 IN NS e.root-servers.net.
. 514903 IN NS k.root-servers.net.
. 514903 IN NS l.root-servers.net.
. 514903 IN NS g.root-servers.net.
. 514903 IN NS c.root-servers.net.
. 514903 IN NS f.root-servers.net.
. 514903 IN NS b.root-servers.net.
. 514903 IN NS d.root-servers.net.
;; Received 228 bytes from 127.0.0.1#53(127.0.0.1) in 0 ms
gr. 172800 IN NS gr-m.ics.forth.gr.
gr. 172800 IN NS estia.ics.forth.gr.
gr. 172800 IN NS gr-us.ics.forth.gr.
gr. 172800 IN NS grdns.ics.forth.gr.
gr. 172800 IN NS gr-aix.ics.forth.gr.
gr. 172800 IN NS grdns-at.ics.forth.gr.
gr. 172800 IN NS grdns-br.ics.forth.gr.
gr. 172800 IN NS grdns-de.denic.de.
;; Received 461 bytes from 128.63.2.53#53(h.root-servers.net) in 135 ms
capital.gr. 10800 IN NS ns0.internet.gr.
capital.gr. 10800 IN NS ns1.internet.gr.
;; Received 109 bytes from 199.4.28.219#53(gr-us.ics.forth.gr) in 201 ms
www.capital.gr. 86400 IN CNAME capital.atoll.gr.
;; Received 60 bytes from 62.1.1.62#53(ns0.internet.gr) in 2 ms
O acima funcionou!
home1:/# nslookup www.capital.gr
;; connection timed out; no servers could be reached
O acima não funcionou!
Enfim, por que eu enfrento esse comportamento diferente do mesmo host?
O problema foi resolvido depois de remover o comando:
porta de origem da consulta 53;