What is a recursive query in DNS when does it become necessary?
When a client or DNS server requests a DNS server to resolve a domain name it can use a recursive or non recursive query. Recursive queries are generally used by clients i.e. PCs and they tell DNS server to respond only with an answer and not a referral.
What is recursive DNS and why is it not recommended?
Why are recursive DNS requests not recommended? Servers that support this type of request are vulnerable to fake requests from a spoofed IP address (the victim of the attack), the spoofed IP address can get overwhelmed by the number of DNS results it receives and be unable to serve regular Internet traffic.
What is a non recursive DNS query?
A non-recursive query is a query in which the DNS Resolver already knows the answer. It either immediately returns a DNS record because it already stores it in local cache, or queries a DNS Name Server which is authoritative for the record, meaning it definitely holds the correct IP for that hostname.
What risks are associated with recursive DNS queries?
Recursive DNS query risks A DNS server that supports recursive resolution is vulnerable to DOS (denial of service) attacks, DNS cache poisoning, unauthorized use of resources, and root name server performance degradation. DOS attacks Servers supporting recursive DNS queries are vulnerable to phony requests that flood a particular IP address with the results of each server’s query.
How many DNS queries?
Straight math says that’s 30,000 DNS queries per month . One visit should be one DNS query. But let’s say that it’s a longvisit that exceeds the 5 minute TTL for that DNS query (and the browser decides to check again). A ten-minute visit might double the queries to 60,000.
Do recursive DNS servers do iterative queries?
Iterative requests are made by both iterative DNS servers and recursive DNS servers. Even the requests made by recursive servers to other DNS servers are iterative. At the level of root DNS, all servers are iterative because they are the end of the line and their availability is crucial to the function of the internet.
How does a DNS query work?
What is a DNS Query, How DNS Query Works. A DNS Query is a request for information sent from a DNS Client to a DNS Server. Normally a DNS Query is a request sent from a DNS Client to a DNS Server, asking for the IP Address related with a Fully Qualified Domain Name (FQDN).