Fix: adjust DNS TTL values based on minimum value (#2706)

This commit adds an updated function that adjusts
the TTL values of DNS records are based on the minimum TTL
the value found in the records list so that all records share the
same TTL value. This ensures consistency in the cache
expiry time for all records to prevent caching issues.

dns/resolver.go

@@ -143,7 +143,8 @@ func (r *Resolver) ExchangeContext(ctx context.Context, m *D.Msg) (msg *D.Msg, e
 			setMsgTTL(msg, uint32(1)) // Continue fetch
 			go r.exchangeWithoutCache(ctx, m)
 		} else {
-			setMsgTTL(msg, uint32(time.Until(expireTime).Seconds()))
+			// updating TTL by subtracting common delta time from each DNS record
+			updateMsgTTL(msg, uint32(time.Until(expireTime).Seconds()))
 		}
 		return
 	}