{"id":"network-plus-free","timeLimitSec":300,"questions":[{"id":"npf-01","section":"concepts","q":"A PC has the address 192.168.10.77 with a /26 mask. What is its network address?","options":["192.168.10.0","192.168.10.72","192.168.10.64","192.168.10.128"],"answer":2,"explain":"A /26 splits the last octet into blocks of 64 (0, 64, 128, 192). 77 falls in the 64 block, so the network is 192.168.10.64 and the broadcast is .127."},{"id":"npf-02","section":"impl","q":"Which protocol prevents layer 2 switching loops by blocking redundant links?","options":["STP","VRRP","LACP","OSPF"],"answer":0,"explain":"Spanning Tree Protocol puts redundant switch ports in a blocking state so frames cannot loop. VRRP is gateway redundancy, LACP bundles links and OSPF is a routing protocol."},{"id":"npf-03","section":"ops","q":"Which DNS record maps a host name to an IPv6 address?","options":["A","AAAA","PTR","MX"],"answer":1,"explain":"An AAAA record holds an IPv6 address; an A record holds an IPv4 address. PTR is the reverse lookup and MX names a mail server."},{"id":"npf-04","section":"secu","q":"Someone plugs a home router into a wall jack and it starts handing out IP addresses. Which switch feature stops this?","options":["DHCP snooping","Link aggregation","Port mirroring","PortFast"],"answer":0,"explain":"DHCP snooping only allows DHCP offers from trusted ports, so a rogue DHCP server on a user port is blocked."},{"id":"npf-05","section":"trouble","q":"A user can ping 8.8.8.8 but cannot open any website by name. What is the most likely cause?","options":["A bad patch cable","A wrong default gateway","An exhausted DHCP scope","DNS resolution"],"answer":3,"explain":"A ping to an internet IP address proves the cable, IP settings and gateway work. If names fail, the problem is DNS."}]}