从几天前开始我就无法访问git-scm.com当尝试ping访问域名时：
ping git-scm.com
我得到一个：
ping: unknown host git-scm.com
如何检查系统配置文件中的错误？我正在运行基本操作系统它基于Ubuntu 12.04并且这似乎是我唯一无法访问的域。
内容/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
nameserver 127.0.0.1
search fibertel.com.ar
（“fibertel” 是我的 ISP 提供商）
以下是 的输出dig git-scm.com +trace：
; <<>> DiG 9.8.1-P1 <<>> git-scm.com +trace
;; global options: +cmd
. 317238 IN NS k.root-servers.net.
. 317238 IN NS l.root-servers.net.
. 317238 IN NS m.root-servers.net.
. 317238 IN NS a.root-servers.net.
. 317238 IN NS b.root-servers.net.
. 317238 IN NS c.root-servers.net.
. 317238 IN NS d.root-servers.net.
. 317238 IN NS e.root-servers.net.
. 317238 IN NS f.root-servers.net.
. 317238 IN NS g.root-servers.net.
. 317238 IN NS h.root-servers.net.
. 317238 IN NS i.root-servers.net.
. 317238 IN NS j.root-servers.net.
;; Received 500 bytes from 127.0.0.1#53(127.0.0.1) in 254 ms
com. 172800 IN NS m.gtld-servers.net.
com. 172800 IN NS l.gtld-servers.net.
com. 172800 IN NS k.gtld-servers.net.
com. 172800 IN NS j.gtld-servers.net.
com. 172800 IN NS i.gtld-servers.net.
com. 172800 IN NS h.gtld-servers.net.
com. 172800 IN NS g.gtld-servers.net.
com. 172800 IN NS f.gtld-servers.net.
com. 172800 IN NS e.gtld-servers.net.
com. 172800 IN NS d.gtld-servers.net.
com. 172800 IN NS c.gtld-servers.net.
com. 172800 IN NS b.gtld-servers.net.
com. 172800 IN NS a.gtld-servers.net.
;; Received 489 bytes from 198.41.0.4#53(198.41.0.4) in 525 ms
git-scm.com. 172800 IN NS ns1.iwantmyname.net.
git-scm.com. 172800 IN NS ns2.iwantmyname.net.
git-scm.com. 172800 IN NS ns3.iwantmyname.net.
git-scm.com. 172800 IN NS ns4.iwantmyname.net.
;; Received 280 bytes from 192.42.93.30#53(192.42.93.30) in 280 ms
git-scm.com. 3600 IN A 62.116.130.8
;; Received 45 bytes from 74.208.254.95#53(74.208.254.95) in 241 ms