This may occur if a hiccup in DNS server has occurred. Apart from making the DNS server more robust or looking for another one, you can also just use the full IP address instead of the hostname. This way it doesn't need to lookup the IP address based on the hostname. However, I would rather fix the DNS issue and prefer the DNS since IP addresses may change from time to time.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…