Administrator Guide

The lifetime parameter configures the amount of time the IPv6 host can use the IPv6 RDNSS address for name resolution. The
lifetime range is 0 to 4294967295 seconds. When the maximum lifetime value, 4294967295, or the infinite keyword is
specified, the lifetime to use the RDNSS address does not expire. A value of 0 indicates to the host that the RDNSS address
should not be used. You must specify a lifetime using the lifetime or infinite parameter.
The DNS server address does not allow the following:
● link local addresses
● loopback addresses
● prefix addresses
● multicast addresses
● invalid host addresses
If you specify this information in the IPv6 RDNSS configuration, a DNS error is displayed.
Example for Configuring an IPv6 Recursive DNS Server
The following example configures a RDNNS server with an IPv6 address of 1000::1 and a lifetime of 1 second.
DellEMC(conf-if-gi-1/1)#ipv6 nd dns-server ?
X:X:X:X::X Recursive DNS Server's (RDNSS) IPv6 address
DellEMC(conf-if-gi-1/1)#ipv6 nd dns-server 1000::1 ?
<0-4294967295> Max lifetime (sec) which RDNSS address may be used for name
resolution
infinite Infinite lifetime (sec) which RDNSS address may be used for name
resolution
DellEMC(conf-if-gi-1/1)#ipv6 nd dns-server 1000::1 1
Debugging IPv6 RDNSS Information Sent to the Host
To verify that the IPv6 RDNSS information sent to the host is configured correctly, use the debug ipv6 nd command in
EXEC Privilege mode.
Example of Debugging IPv6 RDNSS Information Sent to the Host
The following example debugs IPv6 RDNSS information sent to the host.
DellEMC(conf-if-gi-1/1)#do debug ipv6 nd gigabitethernet 1/1
ICMPv6 Neighbor Discovery packet debugging is on for gigabitethernet 1/1
DellEMC(conf-if-gi-1/1)#00:13:02 : : cp-ICMPV6-ND: Sending RA on Gi 1/1
current hop limit=64, flags: M-, O-,
router lifetime=1800 sec, reachable time=0 ms, retransmit time=0 ms
SLLA=00:01:e8:8b:75:70
prefix=1212::/64 on-link autoconfig
valid lifetime=2592000 sec, preferred lifetime=604800 sec
dns-server=1000::0001, lifetime=1 sec
dns-server=3000::0001, lifetime=1 sec
dns-server=2000::0001, lifetime=0 sec
The last 3 lines indicate that the IPv6 RDNSS information was configured correctly.
dns-server=1000::0001, lifetime=1 sec
dns-server=3000::0001, lifetime=1 sec
dns-server=2000::0001, lifetime=0 sec
If the DNS server information is not displayed, verify that the IPv6 recursive DNS server configuration was configured on the
correct interface.
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IPv6 Routing