<optional> ixfr-base <replaceable>string</replaceable> ; </optional>
<optional> ixfr-from-differences <replaceable>yes_or_no</replaceable>; </optional>
<optional> ixfr-tmp-file <replaceable>string</replaceable> ; </optional>
- <optional> request-ixfr <replaceable>yes_or_no</replaceable> ; </optional>
<optional> maintain-ixfr-base <replaceable>yes_or_no</replaceable> ; </optional>
<optional> max-ixfr-log-size <replaceable>number</replaceable> ; </optional>
<optional> max-transfer-idle-out <replaceable>number</replaceable> ; </optional>
<optional> ixfr-base <replaceable>string</replaceable> ; </optional>
<optional> ixfr-from-differences <replaceable>yes_or_no</replaceable>; </optional>
<optional> ixfr-tmp-file <replaceable>string</replaceable> ; </optional>
+ <optional> request-ixfr <replaceable>yes_or_no</replaceable> ; </optional>
<optional> maintain-ixfr-base <replaceable>yes_or_no</replaceable> ; </optional>
<optional> masters <optional>port <replaceable>ip_port</replaceable></optional> <optional>dscp <replaceable>ip_dscp</replaceable></optional> { ( <replaceable>masters_list</replaceable> | <replaceable>ip_addr</replaceable>
<optional>port <replaceable>ip_port</replaceable></optional>