Hi, I'm looking at knot-1.6.1 after have experienced failure with sending AXFR after a zone grew due to enabling DNSSEC, adding a lot of records. I don't know much about iovecs, but isn't this a short write? --8<---------------cut here---------------start------------->8--- libknot/internal/errcode.h: enum knot_error { ... KNOT_ECONNREFUSED = -ECONNREFUSED, ... KNOT_ERROR_MIN = -1000, ... KNOT_ERROR = KNOT_ERROR_MIN, ... KNOT_ECONN, ... }; libknot/internal/net.c: int tcp_send_msg(int fd, const uint8_t *msg, size_t msglen) { ... int total_len = iov[0].iov_len + iov[1].iov_len; int sent = writev(fd, iov, 2); if (sent != total_len) { return KNOT_ECONN; } ... } knot/server/tcp-handler.c: tcp_handle() { ... while (state & (NS_PROC_FULL|NS_PROC_FAIL)) { uint16_t tx_len = tx->iov_len; state = knot_process_out(tx->iov_base, &tx_len, &tcp->query_ctx); /* If it has response, send it. */ if (tx_len > 0) { if (tcp_send_msg(fd, tx->iov_base, tx_len) != tx_len) { ret = KNOT_ECONNREFUSED; break; } } } ... } --8<---------------cut here---------------end--------------->8--- Happy to file a bug report if that's a more proper way of reporting bugs.