Dell PowerConnect 5524P User Manual page 223

After the last IPv4 address is removed from the interface, the ISATAP IP
interface state becomes inactive and is represented as Down, however the
Admin state remains Enabled.
When defining tunneling, note the following:
• An IPv6 Link Local address is assigned to the ISATAP interface. The initial
IP address is assigned to the interface, and the interface state becomes
Active.
• If an ISATAP interface is active, the ISATAP router IPv4 address is resolved
via DNS by using ISATAP-to-IPv4 mapping. If the ISATAP DNS record is
not resolved, the ISATAP host name-to-address mapping is searched in the
host name cache.
• When an ISATAP router IPv4 address is not resolved via the DNS process,
the status of the ISATAP IP interface remains Active. The system does not
have a default gateway for ISATAP traffic until the DNS procedure is
resolved.
• In order for an ISATAP Tunnel to work properly over an IPv4 network, an
ISATAP router is must be set up.
Dell PowerConnect 55xx Systems User Guide
223