Which command can you enter on a Cisco IOS device to enable a scheduled algorithm that directs lookup calls to multiple DNS hosts?
A. ip name-server 192.168.10.14 192.168.10.15
B. ip domain list
C. ip domain lookup
D. ip domain round-robin
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Customizing DNS
Perform this task to customize your DNS configuration.
In a multiple server configuration without the DNS round-robin functionality, many programs will use the first host server/IP address for the whole time to live (TTL) of the cache and use the second and third host servers/IP addresses only in the event of host failure. This behavior presents a problem when a high volume of users all arrive at the first host during the TTL time. For example, the network access server (NAS) sends out a DNS query. The DNS servers reply with a list of the configured IP addresses to the NAS. The NAS then caches these IP addresses for a given time (for example, five minutes). All users that dial in during the five minute TTL time will land on one host, the first IP address in the list.
In a multiple server configuration with the DNS round-robin functionality, the DNS server returns the IP address of all hosts to rotate between the cache of hostnames. During the TTL of the cache, users are distributed among the hosts. This functionality distributes calls across the configured hosts and reduces the number of DNS queries.
In a scheduling algorithm, processes are activated in a fixed cyclic order. Processes that are waiting for other events, like termination of a child process or an input or output operation, cannot proceed and hence they return control to the scheduler. If the TTL of the process times out just before the event (for which it was waiting) occurs, then the event will not be handled until all the other processes are activated.
Check this
https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipaddr_dns/configuration/15-mt/dns-15-mt-book/dns-config-dns.html
D is the right answer
Customizing DNS
Perform this task to customize your DNS configuration.
In a multiple server configuration without the DNS round-robin functionality, many programs will use the first host server/IP address for the whole time to live (TTL) of the cache and use the second and third host servers/IP addresses only in the event of host failure. This behavior presents a problem when a high volume of users all arrive at the first host during the TTL time. For example, the network access server (NAS) sends out a DNS query. The DNS servers reply with a list of the configured IP addresses to the NAS. The NAS then caches these IP addresses for a given time (for example, five minutes). All users that dial in during the five minute TTL time will land on one host, the first IP address in the list.
In a multiple server configuration with the DNS round-robin functionality, the DNS server returns the IP address of all hosts to rotate between the cache of hostnames. During the TTL of the cache, users are distributed among the hosts. This functionality distributes calls across the configured hosts and reduces the number of DNS queries.
In a scheduling algorithm, processes are activated in a fixed cyclic order. Processes that are waiting for other events, like termination of a child process or an input or output operation, cannot proceed and hence they return control to the scheduler. If the TTL of the process times out just be
A is the correct option.
No, ip name-server , will direct calls to second DNS server only if first server fail!!
D, is the right answer because
Ip domain round-robin command
Will distribute calls across the configured hosts
resposta A
https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipaddr_dns/configuration/15-mt/dns-15-mt-book/dns-config-dns.html
The answer should be A