DNS Lookup

What Can I Check with a DNS Lookup?

DNS is the system that translates domain names into IP addresses and other records. With this tool you can look up a domain's A (IPv4), AAAA (IPv6), MX (e-mail), TXT (SPF, DKIM, verification), NS, SOA, CNAME, CAA, SRV, DS and DNSKEY records.

The result shows each record's value and TTL, the response code and the query time. If you enter an IP address, the tool automatically looks up the reverse DNS (PTR) record.

DNS changes may not be visible everywhere until their TTL expires. You can use this tool to check whether a change you made has propagated.

What Is a Ping Test and How Do I Read the Results?

Ping sends ICMP echo requests to the target and measures how long the reply takes to come back. Our test sends 8 packets from our network in İzmir and shows the round-trip time of each packet in milliseconds.

The average and maximum show latency, the loss rate shows how reliable the connection is, and the stability value shows the fluctuation between consecutive measurements (jitter). For real-time applications such as voice and video, low jitter can matter even more than a low average.

Some servers do not answer ICMP for security reasons. In that case ping may look like it failed while the service is still working; try MTR in TCP mode to see the path.

What Is MTR and When Should I Use It?

MTR (My Traceroute) combines traceroute and ping in a single tool. It sends packets to every hop on the path for 10 rounds and shows loss and the last, average, best and worst latency for each one in a table.

It is the best tool for finding the network where a problem starts. If loss starts at one hop and continues on every hop after it, the problem is most likely at that point. Loss that only appears on an intermediate hop is usually caused by the router rate-limiting ICMP replies and is not a real problem.

On networks where ICMP is filtered, choose TCP or UDP mode and a target port (for example 443 for the web) to measure the path real application traffic takes.

How Does Traceroute Work?

Traceroute sends packets with a TTL that increases one by one, making every router on the path to the target identify itself. For each hop it lists the IP address, reverse DNS name, AS number, operator, country and latency.

The results are also shown on a world map, so you can see at a glance which countries the traffic passes through. Private addresses are labelled "private address" and addresses not announced on the internet are labelled "unannounced address".

Hops shown with an asterisk (*) are routers that did not reply. This usually does not indicate a fault; it means the device is configured not to answer such packets.

What Does a BGP Lookup Show?

BGP (Border Gateway Protocol) is the routing protocol networks use to tell each other which address blocks they can reach on the internet. This tool shows the prefix covering the address you enter in our live router table, and every path to that prefix.

The AS path is the sequence of autonomous systems traffic passes through from us to the target; the last link in the chain is the origin AS that announces the prefix. If there are several paths, the one the router prefers is marked "SELECTED".

RPKI status cryptographically verifies whether the prefix is announced by the correct AS. "Valid" means the announcement is authorised, while "Invalid" may indicate a misconfiguration or a possible route hijack.

What Is an Open Resolver and Why Does It Matter?

A recursive DNS server resolves domain names on behalf of clients. This service should only be available to your own users. Servers that answer anyone are called "open resolvers".

Open resolvers are abused in DNS amplification attacks, where attackers turn small queries into large replies aimed at a victim. This tool sends a recursive query from our network to the server you enter and reports the result as OPEN, CLOSED or NO DNS.

What Is a Whois Lookup For?

Whois is the registry system that shows who internet resources belong to. For IP addresses it lists the network name, address range, organisation and abuse contact; for domains the registrar, creation and expiry dates and name servers; for ASNs the AS name and owner.

Domains ending in .tr are queried through TRABIS. Important fields are shown as a summary; you can see the full record in the "Raw whois" section.