diff --git a/src/dns_parser.rs b/src/dns_parser.rs
index f53340b..4f4194d 100644
--- a/src/dns_parser.rs
+++ b/src/dns_parser.rs
@@ -167,6 +167,10 @@ pub(crate) trait DnsRecordExt: fmt::Debug {
     /// Returns whether `other` record is considered the same except TTL.
     fn matches(&self, other: &dyn DnsRecordExt) -> bool;
 
+    fn get_class(&self) -> u16 {
+        self.get_record().entry.class
+    }
+
     fn get_cache_flush(&self) -> bool {
         self.get_record().entry.cache_flush
     }
diff --git a/src/service_daemon.rs b/src/service_daemon.rs
index 617e372..c05245f 100644
--- a/src/service_daemon.rs
+++ b/src/service_daemon.rs
@@ -2363,7 +2363,7 @@ impl DnsCache {
                 // When cache flush is asked, we set expire date to 1 second in the future
                 // if created more than 1 second ago
                 // Ref: RFC 6762 Section 10.2
-                if now > r.get_created() + 1000 {
+                if incoming.get_class() == r.get_class() && now > r.get_created() + 1000 {
                     r.set_expire(now + 1000);
                 }
             });
@@ -2673,7 +2673,6 @@ mod tests {
             FLAGS_QR_RESPONSE, TYPE_PTR, TYPE_TXT,
         },
         service_daemon::check_hostname,
-        service_info::IntoTxtProperties,
     };
     use std::{collections::HashMap, net::SocketAddr, net::SocketAddrV4, time::Duration};