zrhoffman commented on code in PR #7732:
URL: https://github.com/apache/trafficcontrol/pull/7732#discussion_r1297816772
##########
traffic_router/core/src/main/java/org/apache/traffic_control/traffic_router/core/dns/NameServer.java:
##########
@@ -192,7 +193,7 @@ private static void addAuthority(final Zone zone, final
Message response, final
response.getHeader().setFlag(Flags.AA);
}
- private static void addSOA(final Zone zone, final Message response,
final int section, final int flags) {
+ private static void addSOA(final Zone zone, final Message response,
final int section, final int flags, final long negativeCachingTTL) {
Review Comment:
Looks like the argument given for the `negativeCachingTTL` parameter is
always `getNegativeCachingTTL()`. Why not make `negativeCachingTTL` static and
use it directly instead without the function parameter?
##########
traffic_router/core/src/main/webapp/WEB-INF/applicationContext.xml:
##########
@@ -267,6 +267,7 @@
<bean id="NameServer"
class="org.apache.traffic_control.traffic_router.core.dns.NameServer">
<property name="trafficRouterManager"
ref="trafficRouterManager" />
+ <property name="negativeCachingTTL" value="900" />
Review Comment:
This is on the right track. Since `applicationContext.xml` is not
configurable (not [one of the
files](https://traffic-control-cdn.readthedocs.io/en/latest/admin/traffic_router.html#id9)
we list for configuration), this should be a property in one of the
configuration files, maybe `dns.properties`, then referenced in
`applicationContext.xml`.
##########
traffic_router/core/src/main/java/org/apache/traffic_control/traffic_router/core/dns/NameServer.java:
##########
@@ -328,11 +329,19 @@ private static RRset setNegativeTTL(final RRset original,
final int flags) {
if (record instanceof SOARecord) {
final SOARecord soa = (SOARecord) record;
+ // Set the "minimum" attribute to be the
maximum of the current minimum value and 900 (seconds)
+ // This is done to increase the negative
caching TTL, so as to maximize the time interval between
+ // successive NXDOMAIN or NXRRSET responses.
+ final long minimum = Math.max(soa.getMinimum(),
negativeCachingTTL);
+ record = new SOARecord(soa.getName(),
DClass.IN, soa.getTTL(), soa.getHost(), soa.getAdmin(),
+ soa.getSerial(),
soa.getRefresh(), soa.getRetry(), soa.getExpire(),
+ minimum);
+
// the value of the minimum field is less than
the actual TTL; adjust
if (soa.getMinimum() != 0 || soa.getTTL() >
soa.getMinimum()) {
record = new SOARecord(soa.getName(),
DClass.IN, soa.getMinimum(), soa.getHost(), soa.getAdmin(),
soa.getSerial(),
soa.getRefresh(), soa.getRetry(), soa.getExpire(),
- soa.getMinimum());
+ minimum);
} // else use the unmodified record
Review Comment:
Instead of potentially setting `record` twice here, use a condition for
`ttl` field and set `record` only once?
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