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Doing Lab DHCPv6 pushes DNC configuration to clients...

hfakoor222
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Part of the lab mentions:

 

Note:
DHCPv6 SLAAC(Stateless Address Autoconfiguration)
Reason to use DHCPv6 on a network that uses SLAAC is to push DNS and other information to the clients
SLAAC is by far the easiest way to configure IPv6 addresses, simply because you don’t have to configure any IPv6
address. With SLAAC, a host uses the IPv6 Neighbor Discovery Protocol (NDP) to determine its IP address and default
routers. Using SLAAC, a host requests and listens for Router Advertisements (RA) messages, and then taking the prefix
that is advertised to form a unique address that can be used on the network. For this to work, the prefix that is advertised
must advertise a prefix length of 64 bits (i.e., /64). But the most significant of Stateless Address Autoconfiguration
(SLAAC) is it provided no mechanism for configuring DNS resolver information.
Therefore SLACC can be used along with DHCPv6 (Stateless) to push DNS and other information to the clients.

 

 

 

I don't understand how this would push DNS or other information to the clients. Does this mean it pushes prefixes that are the same as the DNS prefix so the client is able to reach it? I had a difficult time interpreting this.

 

Any advice?

1 Accepted Solution

Accepted Solutions

Harold Ritter
Level 12
Level 12

Hi @hfakoor222 ,

It used to be that you could not push dns server information to the clients using SLAAC. You then need to also use stateless DHCPv6 in addition to SLAAC to push the DNS server information. It is now possible to use SLAAC for that purpose.

RFC8106 defines how this is done. It is supported in IOS via the following command under the interface mode:

ipv6 nd ra dns server 2001:DB8:1::1 600

Please refer to the following documentation for more information.

https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipv6/command/ipv6-cr-book/ipv6-i3.html

Regards,

Harold Ritter
Sr Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México

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3 Replies 3

hfakoor222
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Harold Ritter
Level 12
Level 12

Hi @hfakoor222 ,

It used to be that you could not push dns server information to the clients using SLAAC. You then need to also use stateless DHCPv6 in addition to SLAAC to push the DNS server information. It is now possible to use SLAAC for that purpose.

RFC8106 defines how this is done. It is supported in IOS via the following command under the interface mode:

ipv6 nd ra dns server 2001:DB8:1::1 600

Please refer to the following documentation for more information.

https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipv6/command/ipv6-cr-book/ipv6-i3.html

Regards,

Harold Ritter
Sr Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México
Paseo de la Reforma 222
Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México

Thank you

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