From 5bf36f544a78ed71c1bb58b7728914604b5a6df5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Zlatko=20=C4=8Calu=C5=A1i=C4=87?= <zcalusic@bitsync.net>
Date: Sun, 5 May 2019 20:11:58 +0200
Subject: [PATCH] exec: serial behavior (#881)

---
 providers/dns/exec/exec.go | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/providers/dns/exec/exec.go b/providers/dns/exec/exec.go
index 0370eef5..903bcca7 100644
--- a/providers/dns/exec/exec.go
+++ b/providers/dns/exec/exec.go
@@ -105,3 +105,9 @@ func (d *DNSProvider) CleanUp(domain, token, keyAuth string) error {
 func (d *DNSProvider) Timeout() (timeout, interval time.Duration) {
 	return d.config.PropagationTimeout, d.config.PollingInterval
 }
+
+// Sequential All DNS challenges for this provider will be resolved sequentially.
+// Returns the interval between each iteration.
+func (d *DNSProvider) Sequential() time.Duration {
+	return d.config.PropagationTimeout
+}