How does a DHCP server dynamically assign IP addresses to hosts?
A. Addresses are permanently assigned so that the host uses the same address at all times. B. Addresses are assigned for a fixed period of time. At the end of the period, a new request for an address must be made, and another address is then assigned. C. Addresses are leased to hosts. A host will usually keep the same address by periodically contacting the DHCP server to renew the lease. D. Addresses are allocated after a negotiation between the server and the host to determine the length of the agreement.
Correct Answer: C
Explanation:
DHCP works in a client/server mode and operates like any other client/server relationship. When a PC connects to a DHCP server, the server assigns or leases an IP address to that PC. The PC connects to the network with that leased IP address until the lease expires. The host must contact the DHCP server periodically to extend the lease. This lease mechanism ensures that hosts that move or power off do not hold onto addresses that they do not need. The DHCP server returns these addresses to the address pool and reallocates them as necessary.
Which rule does the DHCP server use when there is an IP address conflict?
A. The address is removed from the pool until the conflict is resolved. B. The address remains in the pool until the conflict is resolved. C. Only the IP detected by Gratuitous ARP is removed from the pool. D. Only the IP detected by Ping is removed from the pool. E. The IP will be shown, even after the conflict is resolved.
Correct Answer: A
Explanation:
An address conflict occurs when two hosts use the same IP address. During address assignment, DHCP checks for conflicts using ping and gratuitous ARP. If a conflict is detected, the address is removed from the pool. The address will not be assigned until the administrator resolves the conflict.
The Bigtime router is unable to authenticate to the Littletime router. What is the cause of the problem?
A. The usernames are incorrectly configured on the two routers. B. The passwords do not match on the two routers. C. CHAP authentication cannot be used on a serial interface. D. The routers cannot be connected from interface S0/0 to interface S0/0. E. With CHAP authentication, one router must authenticate to another router. The routers cannot be configured to authenticate to each other.
Correct Answer: B
Explanation:
With CHAP authentication, the configured passwords must be identical on each router. Here, it is configured as little123 on one side and big123 on the other.
Which two tasks does the Dynamic Host Configuration Protocol perform? (Choose two.)
A. Set the IP gateway to be used by the network. B. Perform host discovery used DHCPDISCOVER message. C. Configure IP address parameters from DHCP server to a host. D. Provide an easy management of layer 3 devices. E. Monitor IP performance using the DHCP server. F. Assign and renew IP address from the default pool.
Correct Answers: C, F
Explanation:
The Dynamic Host Configuration Protocol (DHCP) is a network protocol used to configure devices that are connected to a network (known as hosts) so they can communicate on that network using the Internet Protocol (IP). It involves clients and a server operating in a client-server model. DHCP servers assigns IP addresses from a pool of addresses a and also assigns other parameters such as DNS and default gateways to hosts.
When a DHCP server is configured, which two IP addresses should never be assignable to hosts? (Choose two.)
A. network or subnetwork IP address B. broadcast address on the network C. IP address leased to the LAN D. IP address used by the interfaces E. manually assigned address to the clients F. designated IP address to the DHCP server
Correct Answers: A, B
Explanation:
Network or subnetwork IP address (for example 11.0.0.0/8 or 13.1.0.0/16) and broadcast address (for example 23.2.1.255/24) should never be assignable to hosts. When try to assign these addresses to hosts, you will receive an error message saying that they can’t be assignable.
Which two statements about static NAT translations are true? (Choose two.)
A. They allow connections to be initiated from the outside. B. They require no inside or outside interface markings because addresses are statically defined. C. They are always present in the NAT table. D. They can be configured with access lists, to allow two or more connections to be initiated from the outside.
Correct Answers: A, C
Explanation:
Static NAT is to map a single outside IP address to a single inside IP address. This is typically done to allow incoming connections from the outside (Internet) to the inside. Since these are static, they are always present in the NAT table even if they are not actively in use.
A. 0000.5E00.01A3 B. 0007.B400.AE01 C. 0000.0C07.AC15 D. 0007.5E00.B301
Correct Answer: C
Explanation:
With HSRP, two or more devices support a virtual router with a fictitious MAC address and unique IP address. There are two version of HSRP.
+ With HSRP version 1, the virtual router’s MAC address is 0000.0c07.ACxx , in which xx is the HSRP group.
+ With HSRP version 2, the virtual MAC address if 0000.0C9F.Fxxx, in which xxx is the HSRP group. Note: Another case is HSRP for IPv6, in which the MAC address range from 0005.73A0.0000 through 0005.73A0.0FFF.
In GLBP, which router will respond to client ARP requests?
A. The active virtual gateway will reply with one of four possible virtual MAC addresses. B. All GLBP member routers will reply in round-robin fashion. C. The active virtual gateway will reply with its own hardware MAC address. D. The GLBP member routers will reply with one of four possible burned in hardware addresses.
Correct Answer: A
Explanation:
One disadvantage of HSRP and VRRP is that only one router is in use, other routers must wait for the primary to fail because they can be used. However, Gateway Load Balancing Protocol (GLBP) can use of up to four routers simultaneously. In GLBP, there is still only one virtual IP address but each router has a different virtual MAC address.
First a GLBP group must elect an Active Virtual Gateway (AVG). The AVG is responsible for replying ARP requests from hosts/clients. It replies with different virtual MAC addresses that correspond to different routers (known as Active Virtual Forwarders – AVFs) so that clients can send traffic to different routers in that GLBP group (load sharing).
A. It monitors traffic flow and link utilization. B. It ensures the best VRRP router is the virtual router master for the group. C. It causes traffic to dynamically move to higher bandwidth links. D. It thwarts man-in-the-middle attacks.
Correct Answer: B
Explanation:
Object tracking is the process of tracking the state of a configured object and uses that state to determine the priority of the VRRP router in a VRRP group.
A. GLBP supports up to eight virtual forwarders per GLBP group. B. GLBP supports clear text and MD5 password authentication between GLBP group members. C. GLBP is an open source standardized protocol that can be used with multiple vendors. D. GLBP supports up to 1024 virtual routers. E. GLBP can load share traffic across a maximum of four routers. F. GLBP elects two AVGs and two standby AVGs for redundancy.
