我继承了一个用于连接到我们内部服务器的节点来更新和下载包。我已经从内部VLAN取出节点，删除了/etc/apt/sources.list.d/目录，并将其更新/etc/apt/sources.list为如下所示：
###### Debian Main Repos
deb http://deb.debian.org/debian/ oldstable main contrib
deb-src http://deb.debian.org/debian/ oldstable main contrib
deb http://deb.debian.org/debian/ oldstable-updates main contrib
deb-src http://deb.debian.org/debian/ oldstable-updates main contrib
deb http://deb.debian.org/debian-security oldstable/updates main
deb-src http://deb.debian.org/debian-security oldstable/updates main
deb http://ftp.debian.org/debian jessie-backports main
deb-src http://ftp.debian.org/debian jessie-backports main
当我这样做时apt-get update，这就是我所看到的：
Err http://deb.debian.org oldstable InRelease
Err http://ftp.debian.org jessie-backports InRelease
Err http://deb.debian.org oldstable-updates InRelease
Err http://deb.debian.org oldstable/updates InRelease
Err http://ftp.debian.org jessie-backports Release.gpg
Unable to connect to [our internal server]:
Err http://deb.debian.org oldstable Release.gpg
Unable to connect to [our internal server]:
Err http://deb.debian.org oldstable-updates Release.gpg
Unable to connect to [our internal server]:
Err http://deb.debian.org oldstable/updates Release.gpg
Unable to connect to [our internal server]:
Reading package lists... Done
W: Failed to fetch http://deb.debian.org/debian/dists/oldstable/InRelease
W: Failed to fetch http://deb.debian.org/debian/dists/oldstable-updates/InRelease
W: Failed to fetch http://deb.debian.org/debian-security/dists/oldstable/updates/InRelease
W: Failed to fetch http://ftp.debian.org/debian/dists/jessie-backports/InRelease
W: Failed to fetch http://deb.debian.org/debian/dists/oldstable/Release.gpg Unable to connect to [our internal server]:
W: Failed to fetch http://ftp.debian.org/debian/dists/jessie-backports/Release.gpg Unable to connect to [our internal server]:
W: Failed to fetch http://deb.debian.org/debian/dists/oldstable-updates/Release.gpg Unable to connect to [our internal server]:
W: Failed to fetch http://deb.debian.org/debian-security/dists/oldstable/updates/Release.gpg Unable to connect to [our internal server]:
W: Some index files failed to download. They have been ignored, or old ones used instead.
我不确定为什么它仍然试图连接到我们的内部服务器，它是不同VLAN的一部分。谁能指导我？