NS
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... NS ...
... NS ...
...
The RRs that describe cuts around the bottom of the zone are NS RRs that
name the servers for the subzones. Since the cuts are between nodes ...
... in the top node of the
subzone. Since name servers are always associated with zone boundaries,
NS RRs are only found at nodes which are the top node ...
... nodes which are the top node of some zone. In
the data that makes up a zone, NS RRs are found at the top node of the
...
... data required to set up communications with the name servers for any
subzones. That is, parent zones have all the information needed to
access servers for their children zones. The NS RRs that name the
servers for subzones are often not enough for this task since they name
...
... name of the name server is itself in the subzone, we could be faced with
the situation where the NS RRs tell us that in order to learn a name
server's address ...
... delegation effective should be added to the parent
zone. The administrators of both zones should insure that the NS and
glue RRs which mark both sides of the cut are consistent and remain so.
...
... we have a referral. This happens when we encounter a
node with NS RRs marking cuts along the bottom of a
zone.
...
... grandparent, and so on toward the root. Thus if SNAME were
Mockapetris.ISI.EDU, this step would look for NS RRs for
Mockapetris.ISI.EDU, then ISI.EDU, then EDU, and then . (the root ...
... Mockapetris.ISI.EDU, then ISI.EDU, then EDU, and then . (the root).
These NS RRs list the names of hosts for a zone at or above SNAME. Copy
...
...
If the search for NS RRs fails, then the resolver initializes SLIST from
the safety belt SBELT. The basic idea is that when the resolver has no
...
... delegation is "closer" to the answer than the servers in SLIST
are. This can be done by comparing the match count in SLIST with that
computed from SNAME and the NS RRs in the delegation. If not, the reply
...
... TTL of all authoritative RRs to be at least the MINIMUM field
of the SOA, here 86400 seconds, or one day. The NS RRs marking
delegation of the MIL and EDU ...
... root node: the SOA which describes the root
zone and the 3 NS RRs which list the name servers for the root. The
...
... NIC.ARPA., QCLASS=IN, QTYPE=NS |
+---------------------------------------------------+
Answer | <empty> |
...
... that the server is authoritative for the name, and the name exists, but
no RRs of type NS are present there.
...
... NIC.ARPA. |
| 86400 NS A.ISI.EDU. |
+---------------------------------------------------+
Additional | A.ISI.EDU. A 26.3.0.103 |
...
... | NS A.ISI.EDU. |
| NS VENERA.ISI.EDU. |
+---------------------------------------------------+
Additional | VAXA.ISI.EDU. 172800 A 10.2.0.27 |
...
... foreign servers and try to determine the best servers to
query. This search would look for NS RRs for the domains ISI.EDU, EDU,
...
... | NS A.ISI.EDU. |
| NS VENERA.ISI.EDU.|
+---------------------------------------------------+
Additional | VAXA.ISI.EDU. 172800 A 10.2.0.27 |
...
... This request would translate into a type A request for poneria.ISI.EDU.
The resolver would not find any cached data for this name, but would
find the NS RRs in the cache for ISI.EDU when it looks for foreign
...