diff --git a/include/proto/dns.h b/include/proto/dns.h
index 14a6af1..00a6f4a 100644
--- a/include/proto/dns.h
+++ b/include/proto/dns.h
@@ -48,5 +48,7 @@
 unsigned short dns_response_get_query_id(unsigned char *resp);
 struct dns_resolution *dns_alloc_resolution(void);
 void dns_free_resolution(struct dns_resolution *resolution);
+struct chunk *dns_cache_key(int query_type, char *hostname_dn, int hostname_dn_len, struct chunk *buf);
+struct lru64 *dns_cache_lookup(int query_type, char *hostname_dn, int hostname_dn_len, int valid_period, void *cache_domain);
 
 #endif // _PROTO_DNS_H
diff --git a/include/types/dns.h b/include/types/dns.h
index 54bbd02..de9c713 100644
--- a/include/types/dns.h
+++ b/include/types/dns.h
@@ -237,6 +237,7 @@
 	int try;			/* current resolution try */
 	int try_cname;			/* number of CNAME requests sent */
 	int nb_responses;		/* count number of responses received */
+	unsigned long long revision;    /* updated for each update */
 	struct dns_response_packet response;	/* structure hosting the DNS response */
 	struct dns_query_item response_query_records[DNS_MAX_QUERY_RECORDS];		/* <response> query records */
 	struct dns_answer_item response_answer_records[DNS_MAX_ANSWER_RECORDS];	/* <response> answer records */