DNS

DNS service requires the user to define and activate a connection profile, either PSD or CSD.

If not specified, the <cid> and the <preferred_protocol_type> parameters set by means of the +UDCONF=19 AT command are used.

See +CGACT AT command for activating a PDP context.

Resolve name / IP number through DNS +UDNSRN

+UDNSRN

Modules

All products

Attributes

Syntax

PIN required

Settings saved

Can be aborted

Response time

Error reference

full

No

No

No

Section B.2

TCP/UDP/IP Error

Description

Translates a domain name to an IP address or an IP address to a domain name by using an available DNS. There are two available DNSs, primary and secondary. The network usually provides them after a GPRS activation or a CSD establishment. They are automatically used in the resolution process if available. The resolver will use first the primary DNS, otherwise if there is no answer, the second DNS will be involved.

The user can replace each network provided DNS by setting its own DNS for a PSD context by means of the +UDNSCFG AT command.

The DNS resolution timeout depends on the number of DNS servers available to the DNS resolution system. The response time for the DNS resolution is estimated if 8 servers are used to perform this task.

Syntax

TypeSyntaxResponseExample

Set

AT+UDNSRN=<resolution_type>,<domain_ip_string>[,<async>[,<cid>[,<preferred_protocol_type>]]]

+UDNSRN: <resolved_ip_address>

OK

or

+UDNSRN: <resolved_domain_name>

OK

or

OK

AT+UDNSRN=0,"www.google.com"

+UDNSRN: "216.239.59.147"

OK

AT+UDNSRN=0,"www.dau.dau",1,1,0

OK

+UUDNSRN: 0,"172.22.1.201"

AT+UDNSRN=0,"www.rs-ipv6-test.com",1,1,1

OK

+UUDNSRN: 0,"FC01:CAFE::1"

AT+UDNSRN=0,"www.google.com",1

OK

+UUDNSRN: "216.239.59.147"

AT+UDNSRN=0,"www.google.com",0

+UDNSRN: "216.239.59.147"

OK

Test

AT+UDNSRN=?

+UDNSRN: (list of supported <resolution_type>s),"remote_host",(list of supported <async>s),(list of supported <cid>s),(list of supported <preferred_protocol_type>s)

OK

+UDNSRN: (0),"remote_host",(1),(1-15),(0,1)

OK

URC

+UUDNSRN: <result_code>[,<resolved_ip_address>[,<ttl>]]

+UUDNSRN: 0,"216.239.59.147,60"

+UUDNSRN: <result_code>[,<resolved_domain_name>]

+UUDNSRN: 0,"somedomain.com"

+UUDNSRN: -1

+UUDNSRN: -1

Defined values

ParameterTypeDescription

<resolution_type>

Number

Type of resolution operation:

  • 0: domain name to IP address

  • 1: IP address to domain name (host by name)

<domain_ip_string>

String

Domain name (<resolution_type>=0) or the IP address in (<resolution_type>=1) to be resolved. The maximum string length is 128 characters.

<async>

Number

Asynchronous DNS resolution flag. Allowed values:

  • 0 (default value): the final result code is returned only once the DNS response is available, locking the AT interface until the DNS activity is running

  • 1: a final result code (OK or an error result code) is returned immediately unlocking the AT interface and making it available for the execution of other AT commands. Once the result of DNS resolution becomes available, it is notified to the AT interface through the +UUDNSRN URC

<cid>

Number

See <cid>. For more details on the default value of the parameter (where supported), see DNS.

<preferred_protocol_type>

Number

Select the specific IP type between IPv4 and IPv6. Allowed values:

  • 0: IPv4

  • 1: IPv6

For more details on the default value of the parameter (where supported), see DNS.

<resolved_ip_address>

String

Resolved IP address corresponding to the specified domain name

<resolved_domain_name>

String

Resolved domain name corresponding to the provided IP address

<result_code>

Number

Result code of DNS resolution:

  • 0: no error

  • -1: DNS resolution failed. In this case the <resolved_ip_address> or the <resolved_domain_name> fields are not present

<ttl>

Number

The value of TTL received in the incoming packet.

Notes

  • <resolution_type>=1 is not supported.

  • <async> =1 is the default and the only supported value.

  • +USOER error codes are not supported.

  • The oldest of the five possible DNS cache entries persists at Hibernate or Sleep-2 deep-sleep cycle. Refer to +UPSV for more details on the deep-sleep states.

Override DNS configuration +UDNSCFG

+UDNSCFG

Modules

All products

Attributes

Syntax

PIN required

Settings saved

Can be aborted

Response time

Error reference

full

No

No

No

-

+CME Error

Description

Overrides the primary and/or the secondary DNS defined for a selected context identifier.

It is also possible to delete an overridden DNS or list all overridden DNS, the list is empty in case no overridden DNSs are defined.

DNS configuration is only effective if followed by the corresponding <cid> activation by means of +CGACT AT command.

<cid> deactivation and activation is required, if the corresponding <cid> is already activated.

Syntax

TypeSyntaxResponseExample

Generic syntax

Set

AT+UDNSCFG=<cid>[,<index>,<ip_type>[,<ipv4_or_ipv6_address>]]

OK

AT+UDNSCFG=1,1,0,"8.8.8.8"

OK

Read all the overridden DNS for a selected <cid>

Set

AT+UDNSCFG=<cid>

+UDNSCFG: <cid>,<index>,<ip_type>,<ipv4_or_ipv6_address>

[[…​]

+UDNSCFG: <cid>,<index>,<ip_type>,<ipv4_or_ipv6_address>]

OK

AT+UDNSCFG=2

+UDNSCFG: 2,1,0,"8.8.8.8"

+UDNSCFG: 2,2,0,"9.9.9.9"

OK

Delete an overridden DNS

Set

AT+UDNSCFG=<cid>,<index>,<ip_type>

OK

AT+UDNSCFG=1,1,0

OK

Override a DNS

Set

AT+UDNSCFG=<cid>,<index>,<ip_type>,<ipv4_or_ipv6_address>

OK

AT+UDNSCFG=2,2,0,"8.8.8.8"

OK

Read all overridden DNS

Read

AT+UDNSCFG?

+UDNSCFG: <cid>,<index>,<ip_type>,<ipv4_or_ipv6_address>

[[…​]

+UDNSCFG: <cid>,<index>,<ip_type>,<ipv4_or_ipv6_address>]

OK

+UDNSCFG: 1,1,0,"8.8.8.8"

+UDNSCFG: 2,1,0,"8.8.8.8"

OK

Test

AT+UDNSCFG=?

+UDNSCFG: (list of supported <cid>),(list of supported <index>),(0,1),<ipv4_or_ipv6_address>

OK

+UDNSCFG: (1-24),(1-2),(0-1),"ipv4_or_ipv6_address"

OK

Defined values

ParameterTypeDescription

<cid>

Number

PDP context identifier used for the DNS communication. The allowed range is product specific, see <cid>.

The allowed values goes from 1 to 3.

<index>

Number

Index of the DNS to be overridden:

  • 1: primary DNS

  • 2: secondary DNS

  • 3: tertiary DNS

Allowed values:

  • 1, 2

<ip_type>

Number

Allowed values:

  • 0: IPv4

  • 1: IPv6

<ipv4_or_ipv6_address>

String

DNS IP address, see IPv4/IPv6 addressing.

Last updated: Jan 13, 2025
Need help?Contact Support
Questions?Contact us