Anycast DNS
--> In order to understand Anycast DNS, You need to know what is Anycast IP address.
--> Anycast IP address allows you to assign the same IP address to more than one device, unlike normal IP addresses where you cannot use the same IP address on more than one device.
--> Once the Anycast IP address is configured then the routers will forward the request to a destination based upon lowest hop count/lowest cost/lowest latency and others.
--> Anycast IP address mostly used in Content Delivery Networks which are used to provide the content which is closer to the client location.
--> Anycast DNS allows you to configure the same IP address to multiple DNS Servers, No matter in which location they are placed in the world.
--> The DNS configuration is done on one DNS Server propagated to other DNS Servers so that all the DNS Servers configured with Anycast IP address does have the same DNS information.
--> The users need to configure primary and secondary DNS Servers with the Anycast DNS Server IP address.
--> DNS Query from the user will be redirected to the nearest DNS server according to the user location which provides higher performance.
--> Anycast DNS is scalable as we can add more DNS servers with the same IP address without changing anything on the client-side.
--> As multiple DNS Servers are sharing the same IP address which will reduce the impact of the DDOS Attack.
--> Unlike Normal DNS where you require the Load balancer to perform load balancing whereas, in Anycast DNS, You do not require any load balancer to perform the load balancing. Anycast DNS allows automatic load balancing without any load balancer.
--> Anycast DNS provides lower latency because anycast DNS provides the DNS Server which is nearer to the client location.
--> IPv4 addresses do not support the concept of Anycast by default, Only IPv6 does support the concept of Anycast by default.
--> The problem here is IPv6 is not widely used, Most of the organizations are still using the IPv4 address in their DNS Servers.
--> There is a workaround to configure anycast on IPv4 addresses with the help of BGP protocol.
--> DNS Servers like BIG IP DNS will use ZebOS dynamic routing to provide anycast DNS.
Reference: F5.com,
Md. Kareemoddin,
CCIE # 54759
Good article but an even better name!😉
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