[master] shorten default servfail-ttl

4239.	[func]		Changed default servfail-ttl value to 1 second from 10.
			Also, the maximum value is now 30 instead of 300. [RT #37556]

CHANGES

@@ -1,3 +1,6 @@
+4239.	[func]		Changed default servfail-ttl value to 1 second from 10.
+			Also, the maximum value is now 30 instead of 300. [RT #37556]
+
 4238.	[bug]		Don't send to servers on net zero (0.0.0.0/8).
 			[RT #40947]
 

bin/named/config.c

@@ -156,7 +156,7 @@ options {\n\
 	cleaning-interval 0;  /* now meaningless */\n\
 #	min-roots <obsolete>;\n\
 	lame-ttl 600;\n\
-	servfail-ttl 10;\n\
+	servfail-ttl 1;\n\
 	max-ncache-ttl 10800; /* 3 hours */\n\
 	max-cache-ttl 604800; /* 1 week */\n\
 	transfer-format many-answers;\n\

bin/named/server.c

@@ -4107,8 +4107,8 @@ configure_view(dns_view_t *view, dns_viewlist_t *viewlist,
 	result = ns_config_get(maps, "servfail-ttl", &obj);
 	INSIST(result == ISC_R_SUCCESS);
 	fail_ttl  = cfg_obj_asuint32(obj);
-	if (fail_ttl > 300)
-		fail_ttl = 300;
+	if (fail_ttl > 30)
+		fail_ttl = 30;
 	dns_view_setfailttl(view, fail_ttl);
 
 	/*

doc/arm/Bv9ARM-book.xml

@@ -8903,10 +8903,10 @@ avoid-v6-udp-ports { 40000; range 50000 60000; };
 		  without waiting for the SERVFAIL TTL to expire.
 		</para>
 		<para>
-		  The maximum value is <literal>300</literal>
-		  (5 minutes); any higher value will be silently
-		  reduced.  The default is <literal>10</literal>
-		  seconds.
+		  The maximum value is <literal>30</literal>
+		  seconds; any higher value will be silently
+		  reduced. The default is <literal>1</literal>
+		  second.
 		</para>
 	      </listitem>
 	    </varlistentry>

doc/arm/notes.xml

@@ -257,7 +257,7 @@
 	  the cache times out.  This reduces the frequency of retries
 	  when a query is persistently failing, which can be a burden
 	  on recursive serviers.  The SERVFAIL cache timeout is controlled
-	  by <option>servfail-ttl</option>, which defaults to 10 seconds
+	  by <option>servfail-ttl</option>, which defaults to 1 second
 	  and has an upper limit of 30.
 	</para>
       </listitem>