NS ROOT queries to root servers

Medina, Antonio antonio.medina at gibtele.com
Thu Jan 18 19:43:32 UTC 2018

Hi all,

we are running BIND in linux servers. We are using release bind-9.9.4-51.el7_4.1.x86_64

We are not using BIND in an standard Internet environment. Instead, we are using BIND in a mobile network environment, in which DNS Root service is provided by service providers. Therefore, we are no using built-in root servers. So, we have customized the content of db.root file to include IP addresses of DNS servers belonging to our service provider. In our case we have configuration similar to the following one (we have omitted real server names and IP addresses):

. 3600000 IN NS SERVER1.grx.

SERVER1.grx. 3600000 IN A

. 3600000 IN NS SERVER2.grx.

SERVER2.grx. 3600000 IN A

. 3600000 IN NS SERVER3.grx.

SERVER3.grx. 3600000 IN A

. 3600000 IN NS SERVER4.grx.

SERVER4.grx. 3600000 IN A

. 3600000 IN NS SERVER5.grx.

SERVER5.grx. 3600000 IN A

. 3600000 IN NS SERVER6.grx.

SERVER6.grx. 3600000 IN A

We have noticed that each query forwarded towards root servers creates an extra NS ROOT query. We have been reading about "root priming", so were expecting this NS ROOT query upon server restart. However, we are seeing this kind of query for each query that has to be resolved with root servers assistance. We believed that "root priming" was supposed to happen once a day or upon ROOT SERVER TTL, which in our case is 3600, i.e., our root servers are replying with TTL 3600 to NS ROOT queries.

In addition, we have also tested with DNSSEC disabled as follows:

dnssec-enable no;

dnssec-validation no;

Disabling DNSSEC has not made any difference.

How can we stop/limit these massive NS ROOT queries?

In addition, we are going to configure a second provider that has warned us on they do not reply to NS ROOT queries. Could this pose a problem for our DNS servers? Is it possible to instruct our DNS servers not to perform root priming?

Thanks for your help.

Kind regards,


P.S. Below you can find the structure of our named.conf file

acl "ExternalACL" {any;};

acl "InternalACL" {;; };

options {

allow-recursion {;;};

directory "/var/named";


view "InternalView" IN {

match-clients {InternalACL;};

allow-recursion {;;};

zone "." IN {

type hint;

file "db.root";


# Master Zone(s):



view "ExternalView" IN {

allow-recursion {;};

allow-transfer {none;};

match-clients {key gibraltar-externalview-smkey;!gibraltar-externalview-other-smkeys;ExternalACL;};

zone "." IN {

type hint;

file "db.root";


# Master Zone(s):



Antonio Medina Ortega
Broadband & Transport Networks

Mob: +350 58008261
Fax: +350 20071673
Email: antonio.medina at gibtele.com<mailto:antonio.medina at gibtele.com>
Web: www.gibtele.com<http://www.gibtele.com/>

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