diff --git a/dns/cache.go b/dns/cache.go
index 03be604..87aa2aa 100644
--- a/dns/cache.go
+++ b/dns/cache.go
@@ -5,8 +5,8 @@ import (
 	"time"
 )
 
-// HundredYears is one hundred years duration in seconds, used for none-expired items
-const HundredYears = 100 * 365 * 24 * 3600
+// LongTTL is 50 years duration in seconds, used for none-expired items
+const LongTTL = 50 * 365 * 24 * 3600
 
 type item struct {
 	value  []byte
diff --git a/dns/client.go b/dns/client.go
index 7f633f9..3c61889 100644
--- a/dns/client.go
+++ b/dns/client.go
@@ -218,7 +218,7 @@ func (c *Client) AddRecord(record string) error {
 	binary.Write(&buf, binary.BigEndian, uint16(len(b)))
 	buf.Write(b)
 
-	c.cache.Put(getKey(m.Question), buf.Bytes(), HundredYears)
+	c.cache.Put(getKey(m.Question), buf.Bytes(), LongTTL)
 
 	return nil
 }