cache = $memcache->createLocal('NegativeDnsCache'); } private function createCacheKey(string $domain, int $type) : string { return $domain . '-' . (string)$type; } public function setNegativeCacheForDnsType(string $domain, int $type, int $ttl) : void { $this->cache->set($this->createCacheKey($domain, $type), 'true', $ttl); } public function isNegativeCached(string $domain, int $type) : bool { return (bool)$this->cache->hasKey($this->createCacheKey($domain, $type)); } }